I have an HP Envy 17 that I got in 2012 and it took a shit.   It won't power on, when you push the power button the power and F10 button's lights flash on for a second.   That's all it'll do.   I took it apart and I see nothing obvious, I tried it without the HD and with each of the RAM sticks by themselves.  It has always ran hot as hell.   It appears to me that the motherboard is bad.   I can get a motherboard for less than $100.   Do you think it worth it to replace the motherboard or should I just get a new laptop?

Well, I pushed the power and F10 at the same time and after sitting for 10 or 15 minutes it turned on.  Anything I should try while it's on? 

Make a complete backup?

I'm good  with the backup, I meant as afar as figuring out whats wrong with it.   I noticed that when I didn't start the LED by the power plug would cycle between white and red being mostly red.  Now it is white again.   Maybe the power brick is going bad?  The battery is bad.  I use it like a desktop so I haven't bought a battery for it.