Dv6700 confused on which is causing issue

The paste did not "melt". You are looking at two different products designed for different use.

The paste on the CPU looked like that shortly after installation, so it's doubtful it would suddenly be the problem. It does sound like too much may have been used.

Probably your problem is elsewhere.

so im guessing do the oven trick or reflow?

check all connections .remove ram cmosbattery and hdd.turn on cpu if u get beep sound.then check cmos battery has enough power or buy a new one and plug the buyed. insert ram.power on.press f2 and del keys.if u get bios then no problem.All problems are solved.

The cause can be bad memory in a laptop, some don`t boot if the case. The thing about the dv6700 laptops had to do with the nvidia 8400, or 8600 graphics chip alot of them were recalled due to a fault in the chips, they tended to fail under heat and the solder melted on the underside of the chip connecting it to the board. That was the most common fault with them. The result a black screen and no bios post. A re heat of just the graphics chip may fix the problem, but I would use a heat gun, pass it around the chip in circular motion about four inches away fron the chip no more than 15 seconds a pass four circular four or five passes should do it. leave it to cool about 20 mins if your lucky it may work, or the chip has died due to excessive heat build up over time of use. In that case its done for I am afraid Chrism.