Sir Sashikanta . . . .
Sure looks like your AC power took a lightning VERY-VERY-VERY nearby.
Since the AC powered " HOT" half of the power supply probably initially took out the DC rectifiers and then popped the switching transistor that you see mounted to the heat sink and the excess power pull then was enough to vaporize foli traces on two porions of the HOT side of the board.
The "cold" side with its two side mounted dual schottkey rectifiers might have ecped as massive state of destruction.
Considering that I only see a single ended 12VDC coming out, here might be your poor boys evaluation . .solution .
Commandeer one each motorcycle or car battery, since that can far exceed your maximum amp capacity needs .
Get the stystem connected up with an incoming audio source such that the speaker is
READY to put out sound just as soon as 12 VDC power is
applied.
Then hook up the negative of the battery to the amp and get ready and then initially just rapidly brush the + battery conection to the + input of the amp to expect aburst of music from the unit.If so then try out for a couple of seconds and then pull out your DVM and set to DC amps in its 10 amp range and insert its leads in series with that precviously applied 12VDC from the battery. Then observe the current pull and run the volue up to max to see your greatecst current pull of the unit.
I think that your original unit was putting out 14V DC and was peaking out at 2 Amps on heavy sustained bass.
Here is he IC that the power amp was designed around and as you can see a 14VDC supply was at the very bottom spec of those shown.
http://pdf1.alldatasheet.com/datasheet-pdf/view/234817/STMICROELECTRONICS/STA540.html
An AC line derived 14V-15 DC power supply twice that 2 amp rating should have one cool running unit.
Thassssit . . . . .
73's de Edd
