HP T740 thin client BIOS dump?

[Greg_E]

I bought a bunch of HP T740 thin clients cheap because the BIOS was locked, I figured I could unlock them, but looks like I need a little help. I looked over both sides of the board, and the only chip that might be what I need is locked in a socket, a Winbond 25x128. I did not find another chip that looked like it could be a password eeprom like some other HP devices (Elite Desk 600 g6 which I was able to fix).

So lacking the pins I need to adapt my EZP2019, I tried the Windows BIOS installer and the copy to fix other computers option. It did give me a 16MB .bin file. When I dropped it onto RCunlocker, it said "missing unlockable content".

Does this mean I can flash this version onto itself (or another computer) and unlock the BIOS? Seems to easy. Or am I going to need to build an adapter to connect to the BIOS chip and dump it with the programmer? Pulling the chip out may be a one time deal, and then the socket cover may break and not retain the chip, so I'm hesitating to just rip it out. Need to make some pins to reach inside and then clamp onto those extension pins to be safe (and hope in circuit programming works).

I've been searching on and off for a few days, mostly I see people attaching their bin file and someone else giving them an unlocked version. I do have a hex editor and can edit this "generic" BIOS if someone can clue me into the area that needs to be changed to wipe out a password. I'm guessing that area is blank so that the flash will retain the password on the rescued machine, and that maybe filling it would over write to wipe it out, but just a guess.

Any insight into what I'm doing wrong, or what I need to do would be welcome.

[Greg_E]

OK, I'm at a loss here. I pulled the BIOS chip, put it in a socket and tried the EZP2019+, no dice. Tried it in a CH341a V1.7 set to 3.3 volts and it was detected and read to a bin file (attached). I dropped it onto RCunlocker and it still could not find anything to unlock.

This is a Winbond 25q128jv chip.

There is also a Winbond 25q16jv on the board, I dumped that with in circuit clips but it was detected and seems to have dumpd. I also tried dropping that on RCunlocker, still no dice with the same nothing to unlock. Also attached.

I'm using Windows 11, is that part of the problem? I have a win10 computer I can try if that might be the issue. Or am I just doing something wrong here???

Serial number is MXL150289V
product 1Y6B9UC#ABA

Using RCunlocker v1.0

[hoaca388]

Serial number is MXL150289V
product 1Y6B9UC#ABA

HP t740 Thin Client Bundle (1Y6B9UC)

[Greg_E]

Thank You! Is there a way to enter the serial number again? The system doesn't seem to mind since it boots and I'm running a Linux live disk to type this, just wondering if it will give me trouble with some operating systems. Target for these is XCP-ng to move my lab from big noisy servers to little mini-computer system, I don't need the processing power for my lab and these should be OK once I jam max memory into them.

I may have made a mistake with this too. What I did was erase the BIOS, then flash the above to the chip through a CH341 v1.7 programmer. Was I supposed to just use the HP flasher to flash this version? I can restore the original BIOS if needed, but if it doesn't matter, then I won't spend the time pulling the chip back out. And can I use the above version for other computers (I have 4 more) that I'll need to flash.

I have new (blank) BIOS chips on order, should be here next week. I'll play with different options when they arrive and I can afford to brick some of these new chips.

[Greg_E]

OK, here is the answer I finally went with, I may not be understanding what I need to do with the file above.

I used a CH341a v1.7 programmer and a spring loaded socket for the chips. 3.3 volt setting.



First things you need are the specific information from your device, Serial number, Build ID (BID), feature byte, product number. You can pull these from your current BIOS, if it asks for a password, just hit enter 3 times and you'll be able to see the information. This should also be on stickers under the back/bottom cover.



Open the front side and locate the BIOS chip (no EC in these devices). Press straight down to compress the springs, then slide the cover in the direction of the arrow, it should pop open when you release the pressure. Put the chip in the reader and read out the BIOS, store that somewhere. I used NeoProgrammer. Once you know that you have the old BIOS saved, you can proceed.






You will need to download the HP bios updater and extract the files to where the factory M42_xxx BIOS version is available. Open this bios in NeoProgrammer, erase the chip, and write to the chip. Verify the chip. Put the chip back into the computer and reverse the process to slide the cover in place.



First boot will take a long time, just keep press/release on esc key or f10 key until it gives you the menu/bios.

arrow over to Security, arrow down to System IDs and press cntl+a which allows you to edit the information.



Fill in the info from your sticker, be very careful with the Feature Byte, all of mine were the "no OS" version of the device, and had the same feature byte. If you have a Windows and ThinOS machine, that feature byte will be a product key and different for each build. Enter without the spaces.



Make any other BIOS changes you want, and save and exit. when it reboots you can go back into BIOS and check to make sure everything is correct. You can not edit the feature byte again, you would need to wipe and flash the bios again to change the feature byte.