Looking at the manual for light diagnosis (https://www.dell.com/support/kbdoc/en-uk/000123890/precision-t3500-t5500-t7500-workstations-diagnost…), it says “PCI device configuration activity is in progress or PCI device failure was detected.” I opened and check (volt meter) the PCI cables one by one and it seems all of the give the right amount of voltage.
If I keep the PC unplugged and plug back, then the 2nd light stays ON. I am able to turn ON the Windows. But, after shutting down once, the Windows won’t start (light 1 & 3 blinking a few times) until kept unplugged for sometime. I ran the system diagnostic (BIOS) and it didn’t find any issues! I have also checked the battery, drained the power by holding the power button.
Once, it gave me the message that the “previous processor thermal failure” & “system battery voltage is low”. This message only appears once.
Strange, if the processor is failed why it turns ON sometimes. The battery is replaced, so why low.