The missing part in your story: how could you install Windows Vista in a PC that doesn't power on?
Anyway, it might be time to replace either the PSU or the motherboard.
Kees
My Acer 4520 was working fine last night and this morning nothing. No lights, no sound nothing. Put in a different hard drive and re installed windows vista. Then use the laptop for hours everything was working great. Then this morning nothing????

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