Hello, I have an old Tandon ANT-4D33 notebook with a 486DX processor. A little while back, while getting it going we fixed the built in power supply. I didn't have a plug pack, so we made a home made connector that I could hook directly into my 12v power supply from an old computer.

We had to bypass a dead fuse, and after we did everything worked fine. However, one day I accidently plugged in the connecter the wrong way around, reversing the polarity. Within a few seconds my power supply kicked, detecting the fact I had reversed the polarity.

Ever since then, the built in power supply has not been powering up, despite correctly inputting the voltage. We have searched around the power supply board, checking all the diodes and fuses we can see, but they all appear to be working.

Have I gone and killed the laptop, what damage would have been done, what components could be the issue?

Its a wonderful best, the last thing I would want is to have killed it 😒

Thanks.

P.S: An image of the power supply is attached.