Even I am facing the exact same problem with my HP pavilion entertainment PC Laptop
1. Sometimes, on-button glows, recognizes cd-drive, fans etc.... then nothing happens, not even POST. I mean a complete blank screen. num-lock,capslock do not glow. the sound os and wireless led are orange instead of blue.
2. Some other times, it boots normally and works completely ok till I shut down or restart.
Repairman told me maybe Mother board is screwed but then if that is the case, then why should it work sometime and sometimes not? i tried to reboot it a couple of times wich worked in the beginning but not anymore...
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