Dell Latitude 5530 BIOS Password Removal Attempted but I Broke the Laptop

[TopPop]

Sorry for the long story. I have a Dell Latitude 5530 (i7) laptop (South Peak 15 MLK MB DDR4 203102-1 FK8VG$JA) with an admin BIOS password that I want to remove. Service Tag: HYKFPT3. Other than that the laptop worked OK.

I found a CH341A Black and went looking for the BIOS chip on the motherboard. After trying to read one chip that was a firmware chip but not the BIOS I think I found the BIOS chip labeled Winbond 25Q256JVEN. Altogether I think I found 4 different firmware chips in the laptop. The BIOS chip is a WSON8 6x8. I used the CH341A, NeoProgrammer, and a cheap pogo pin clip to dump the BIOS. After several tries I got two matching dumps and thought I had a good read but UEFI Tool and the BIOS patcher program told me the dump wasn't recognized as being Intel, basically telling me the dump didn't make sense.

Did some Googling and learned about the CH341A Black running chips at 5V! I found instructions for modding it to do 3.3V. I did the mod and confirmed it was working. Did some more reads of the chip and again got multiple dumps that were identical. For some reason it didn't occur to me to verify the data read with the data still on the chip. Anyway, the 'good' dump was recognized by UEFI Tool and the BIOS patcher program so I patched it.

Using pogo pins I connected to the W25Q256JVEN and erased it, reprogrammed it, and attempted verification. Verification kept failing. I tried reprogramming and verifying several times, changing some things with my setup, but always failed verification. I got fed up with the CH341A. I noticed the anchor points to the USB shell were loose, even though I hadn't been rough with it, and a pin in the shell running to a point on the circuit board didn't look like the solder had flowed properly in to the joint. I reflowed the USB connections, fixing them, but I still had failed verifications. I decided to buy a XGecu T48.

I had sort of worn down the tiny pads around the WSON8 BIOS chip from the pressure I was applying with the pogo pins to get a good read so I tried reflowing the pads to refresh them in case that might help get a better connection.

After waiting a few days the T48 arrived and I took all the hardware I was working on home with me and set up the software and hardware at my home computer. I couldn't get the T48 to auto detect the W25Q256JVEN. I set the chip manually. Then when I tried to write with the T48 software it said the chip ID wasn't right. The software for some reason thinks the chip ID is 00 00 00. So, I unchecked the chip ID check option. Basically, it looked like the software pretended to write the chip and then the chip instantly failed verification. To be fair, I'm a BIOS programming noob. I might be doing something wrong, possibly several things wrong. I really don't know. The T48 software looks more complex. I'll try getting help from XGecu about the T48.

At this point I was annoyed with the T48 so decided to give the CH341A Black another try. It wrote and verified the chip on the first try! I guess trying it at home made a difference but I have no idea why.

I reassembled the laptop and tried turning it on. The power button light turned on for about 30 seconds and then turned off. That is all that happens every time I try the power button. No Caps Lock or Num Lock light and no backscreen light and no fan spin. Somehow I broke the laptop.

First I tried BIOS recovery from USB drive. The process is plug in a USB drive with the BIOS recovery file, unplug the laptop, press and hold Ctrl and Esc and plug in the charger. The light in the power button automatically turns on and after waiting about 30 seconds the power light on the USB drive flashes once and the battery charge indicator light on the front of the laptop flashes white once and then the power button light turns off. The backlight never turns on. The laptop just shuts itself off and doesn't recover the BIOS.

Next I tried the system board built-in self-test (M-BIST). The laptop starts as powered off. I press and hold M and the power button. The laptop power button light turns on and after about 30 seconds I see the USB drive power light flash and then the power light turns off. The Internet tells me if the battery status light turns on amber then the system board has failed. In my case the power button light just turns off and the battery status light doesn't turn on so I guess that is good.

Last, since the screen has stayed off each time I tried something I decided to try running the built in LCD test. I pressed and held the D key and pressed the power button. The screen cycles through the colors like it should so the screen does work. After the colors the laptop keeps the power button light on for a bit longer and then turns off but the power light on the USB drive turns on, stays on, and the battery status light gives me a 3 amber and 5 white blink code which means a power rail failure according to the laptop's documentation. Though, sometimes when I've tried this I only get 3 amber blinks. The white part is left out somehow.

I'm guessing maybe all the pressure I applied to get the pogo pins to work messed up something. When I first used the pogo pins I checked the perimeter of the chip for any components that might be in the way and it looked clear. I also put a stack of medium sized post-it notes under the board to avoid putting pressure on the ports at the edge of the board and flexing the board. However, when I was reassembling the laptop I looked more closely and saw a tiny component very close to the BIOS chip that may have been in contact with the rectangular plastic shell that goes over the chip when the pins are applied. The component is still there but it is very tiny (seriously, I didn't see it the first time I looked and I almost can't see it) and maybe it is broken now. Or, maybe there is a problem with the BIOS chip itself that I caused by messing with the pads. I have a replacement chip on the way though my soldering skills aren't that good. I do have a hot air station.

Based on the blink code I have a power rail failure. Though, I wonder if the laptop might be giving that blink code just because the BIOS chip isn't working or that tiny component next to the chip is broken. What should I try next?

[simshady]

The wson chip in this laptop uses 1.8v logic, and I don't think its 3.3 tolerant. Hopefully the new chip will do the trick

[TopPop]

I wondered about that. I was using this datasheet for reference so I thought 3V was OK. On page 92 of the PDF I see Product Number: W25Q256JVEIN, Top Side Marking: 25Q256JVEN which is the chip I have on the laptop motherboard.

NeoProgrammer auto detects the following:



I ordered a replacement chip from eBay and it has arrived but I noticed it is missing the pin 1 dimple. It just looks odd. I might just experiment with it and order another chip from someplace like Digikey.

[mon2]

Post a pic of the chip. The vendor may will have a pin 1 designation but may be different from earlier batches.

[TopPop]

Post a pic of the chip. The vendor may will have a pin 1 designation but may be different from earlier batches.

Original chip on the board:


Replacement chip on the board:


I guess I'm just uncertain about the lock of the dimple but maybe it really doesn't matter.

After I discovered that the motherboard wasn't working I was worried that maybe I broke some components near the BIOS chip off the board by using the pogo clip.



I found a boardview and schematics on this forum and downloaded them, also attached here. I was looking at the boardview and schematics and was worried I was missing R24B6. Then I remembered I took a pic of the original BIOS chip before I started messing with it. In the picture it looks like R24B6 was never there. I was also worried I put too much pressure on R6849 by pressing the plastic shell of the pogo clip on to it and broke it. According to the schematic it is 100 Ohms. My multimeter showed me it is still 100 Ohms.

I had to crank the hot air station all the way up to get the original BIOS chip off the board. I cleaned the pads and used leaded solder to put the new chip on but I think I forgot to turn down the temperature when I soldered the new chip. Before putting it on the board I programmed it with the patched BIOS. After assembling the laptop enough to turn it on it would show the light in the power button for about 30 seconds, then turn off for a moment and then turn itself back on for another 30 seconds. Basically it was behaving the same as before except now it tries to turn on twice instead of once before powering off completely.

As of now I reprogrammed the new chip with the locked BIOS. I'm just curious if maybe the motherboard will start working again with the original BIOS. The BIOS_IMG.rcv for this laptop is 51,256,424 bytes. Maybe something more than just patching the BIOS firmware needed to be done. Maybe I needed to do something with the firmware on another chip on this board?

Going back to the locked BIOS didn't fix it. Still the same power button light for 30 seconds, then off, then back on again for 30 seconds sometimes. If I do the D + Power Button it cycles through the colors and after it finishes it does not give any blink code, unlike earlier when it gave the code for power rail failure.

I attached my original BIOS dump and the unlocked dump in case it helps somehow.

[TopPop]

I think I will return the XGecu T48. Unfortunately the ZIF socket usually doesn't work. I did get it to work a few times but each read of a chip I tried was completely different.