So I was working on my raspberry pi and it suddenly shut itself down without any warning whatsoever. I re-plugged my power supply and even though the PWR led is red the pi won't boot up an OS. Initially the ACT led did not glow but after leaving it aside for a day, the ACT led started blinking but the pi still does not load an OS.
Things I have checked so far -
There is no problem with the power supply as another pi boots up perfectly from it. Also the supply gives 5.3+ V and 700+ mA current. And most importantly the borked pi was running on the same power supply for a year!
SD card is not an issue since another pi boots up perfectly from it. Also I've tried with another SD card with NOOBs on it. The borked pi still does not respond.
Checking voltages on TP1 and TP2 points shows that the pi has ~5.20V
I feared the polyfuse had blown up because earlier I was reading ~4.8 V of voltage. But after letting it cool down for a day I checked again. Voltage into the fuse is ~5.28V and out of the fuse is ~5.23V
No response on the HDMI/monitor too. Nor any response to keyboard interrupts.
I have been trying to research what could be the possible issues but not found anything useful so far. But I've noticed that it gets heated up too much near the microusb port and on the processor itself. Sometimes its too hot that I can't even touch it for more than a few seconds. This does not seem to be the case with my other pi that runs happily for hours without heating up so much that I can't touch it.
FWIW, a few minutes before the pi got borked I was testing some code to run a servo motor directly attached to the pi. I had only plugged in the control pin to the pi while the motor itself was powered separately from a 12 V battery. Only the ground pin of the pi was connected to the ground terminals of the battery and the servo (as that is what the tutorial said). The pi ran fine for half n hour or so after I disconnected the whole setup.
What can I do? Is it really borked and it's time to let it go?