ESR tester repair

[vari21]

Hi everyone.
Sorry if im not posting my problem in the right place also about my poor english.
Im trying to repair an ESR tester based on atmega 328, i ve got it from ebay, it comes as a DIY kit. the device has worked succesfully after soldering all it components together.but after a stupid mistake from me (over voltage or backward power plug i dont remember) it stopped working now ,when i push the ON button it wont turn on, i can see the screen lighting up for a half second and after that it stops completely.
i suspected these components atmega328, HT 7550,TL431,and maybe also the s9012 and s9014 but im not electronician skilled i ve already checked all the connections of the board they are OK.
so i need a support from the masters here in order to help me repairing it.thanks in advance.

 

[Bluejets]

I wouldn't bother with it since a complete tester can be had, case and all for less than the price of the kit in some instances.

However, It's a fairly basic power supply and with a multimeter you should be able to do some initial voltage checks etc.
They are marked on the schematic and there is a good chance the transistors or the voltage regulator would have saved the microcontroller.
Do that and then get back here again with some detailed results.