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No Boot, Screen Flash, White LED, Black Screen. Logic Board Repair? much like this question, i have 2 logic boards here that pass the visual inspection, no corrosion or signs of any issues. when i plug them in and power them up, the screen flashes white, goes black but computer stays running. no sign of activity on an external monitor either. is this something that can be fixed? thanks!

If connecting to a external monitor yields the same results, then it is safe to say you have a logic board/GPU issue. Unless your skilled in component level repair you will not be able to salvage the boards. There are a few patrons here who now of vendors that perform such repairs. Hopefully, someone will chime in soon with a link.