Lenovo ThinkPad E14 Gen 5 - Not Powering On - 3 Blinking Lights - 20 volts 0.224 amps

[bialag]

Hello,

I have a Lenovo here that does not want to power on. The motherboard appears to be clean, no sign of corrosion or obvious fried components. When plugged in, I see 3 blinking lights and then off. It would cycle the 3 blinking lights every 10 seconds or so as long as I have the adapter plugged in. Amp meter shows 20 volts, 0.224 amps, no fan spin, red light indicator near the charge port.

Thermal camera shows a section of the motherboard that is warmer than the rest. It is near the connector labels JRTC1 (CMOS battery). Diode measurement to ground for pin 1 = OL, pin 2 = 0.00. The resistor connected to pin 1 is 10K and OL on both sides. This area heats up whether or not the CMOS battery is connected or not.

Also, when I disconnect the battery and connect just the adapter, the same area does not warm up. I attached some pictures to show thermal camera while adapter is connected versus disconnected.

Just wondering if anyone has advice for me on what I should check next? I am in the process of searching for a schematic / board view so I can continue with the troubleshooting as well.

[Aliencomputres]

Diode measurement to ground for pin 1 = OL, pin 2 = 0.00 its shorted.Pull out diode and measure it.

[pc_okay]

Check Amp meter without battery.
Please give us motherboard Number to look for schematic or BV.

[bialag]

Model number is NM-F311 KE611 / KE451 Rev 1.0

Amp meter without battery is the same: 0.224~

It appears that what's heating up is on the other side of the board is the BQ chip. BQ25710? Or it's BQ25730? It is hard to read. PU4000 about 60 celsius. This heats up when battery is connected, might be normal.