Had the same problem. Went the lazy man´s path and replaced the power jack board. About $ 50.00 and now it is up and running.
Consider this: medium cost labour/low cost parts vs low cost labour/high cost parts. On top of that limitations in know how.
I am learning electronics step by step from zero. Just didn´t have enough patience and time to wait until I could solve it replacing components.
Hope it gives some insight.