My (project machine) Dell Inspiron 15R SE 7520 laptop has started hanging while powered off or sleeping, with the power LED still blinking but the machine not responding to any external inputs (opening the lid, pressing the power button, holding it down). I assume the EC microcontroller is hanging, but I don't know why that is. I took the laptop apart, took the coin cell battery out and put it back in, and the problem stopped for a month or so but has returned.
What's causing the issue? Perhaps the coin cell battery is drained (and I didn't know the right way to test CR2032s at the time, so I thought it was good)? Or is the EC fried or corrupted, perhaps because I did a botched BIOS reflash which corrupted the EC, and had to reprogram the EC in flashrom over multiple passes while skipping "hung" flash blocks (the pin to hold the EC in reset didn't make flash properly writable)? Afterwards the laptop would boot, but dumping the EC flash again revealed the image was changed again. Or did the EC die due to flash corruption that occurred afterwards (either from flaky chips or because I damaged it earlier)?