For $29/mo, we provide access to advanced level technicians who will answer your questions on any Macbook board related matter to the best of their knowledge promptly & walk you through how to solve your problem so you can deliver a working board to your customer.
I have a 820-2530-a board that sometimes does not boot, i have black screen and the white led stays always on,
but when the system boots is stable for an entire day!
Aaah, so the board starts always.
But sometime stays on without any activity.
Be sure no USB activity that moment.
Use USB OSX pendrive with LED link, to be sure; disconnect internal HDD.
Check if CPU gets voltage and see if drops a bit after few seconds.
Clean RAM slots and check one memory module at a time, each slot by separate.