A friend of mine asked me to look at his laptop. It would over heat and shut down after thirty minutes. When I looked at it someone had already opened it up. The inside was a mess of dust crammed in the fan intake, crumbs, and crust from maybe a liquid spill. I cleaned it up, put it back together andf all I get is lights on the cap locks and number lock keys flashing. It is a HP Pavilion g7. It has no sounds of life except the lights flashing. Should I tell him to buy a new laptop?

It was working before you cleaned it up? Check again for broken connections and such. Make sure all socketed chips are well seated and that their connections are clean also. A can of compressed air is your friend here... :-) I think it is worth a second pass on the cleanup. If it still doesn't boot, then it is time either for replacement (something other than HP), or a visit to the HP repair depot.

It was not working when I received the laptop, it looked like someone had opened it up and made matters worse. I am going to go over it again.

i would prefer you to buy a thermal pad so that the excessive heat from laptop will radiate faster.