Answer to "Reversed Polarity on DC Power Supply. Can I replace Fuse/Diode on MB?"I know it’s late, but I have the same problem, and feel obligated to document the process for anyone else. I reversed the polarity, and have precisely the same symptoms as you described. I decided to run the power backwards again (can’t kill it twice, I hope) and felt around with my fingers for any components that were heating up (MOSFETs tend to fail short circuit). I noted the chips shown heated up (see attached) and so I will try to replace them, and see if the problem is resolved. I’ll report back with the results. (Ignore the wires and glue, the DC socket broke, and this is a temporary bodge to feed power to the laptop.