Buy a new one being you obviously don't have the knowledge, tools or the skills to fix this one.

How are you figuring out where power is by poking things with a screwdriver?

I have two of these with slightly different board layouts. I'll post a photo of both sides of the 1st older board (7-2012) I'm working on. It has power on the high voltage header (300+V) but no power on the mid header which should be about 35v. The mid header is in the middle by the BCK2801-2007 transformer. I took out the aluminum partition against the chip TOP256EN. I've gone over a lot of the components with my multimeter and just not sure which one is bad in the mid tier stack. There's no voltage below the midrange header so something isn't feeding the midrange. The question is what exactly. I suspect the midrange transformer or the IC chip TOP256EN but don't want to randomly swap parts so would rather get a really good idea on where exactly the problem lies.

Moderator edit: new thread created from this.

 

D5 has been removed?

 

Here is the circuit diagram from the datasheet, check it out and see if it's the same as yours..D5 on your pcb is D2 on here..

 

Running it with that diode missing will cause large voltage spikes on U1 and will probably destroy it.

 

I have repaired a few of these, faults have all been mechanical, with faulty contacts on the battery connect tabs.