My sons HP laptop that is 20 months old has developed a fault.
When turned on earlier the screen was all crazed (like a TV out of tune) and it turned itself off before fully loading. We took the battery out and then reattached it and started it up again. This time the screen was fine but again it died before fully loading.
The battery has not held a charge for some time so he always runs it off the mains.
Can anyone help from the rather vague symptoms described?! I'm hoping that it is just the battery but as he is running via the mains this would seem odd to me (but then I know nothing about laptops).
If it's turning off immediately, it doesn't sound like overheating.
If the initial display is OK, and then it goes weird before turning off, it could be a video driver problem. Try starting it in safe mode. If that works then try a system restore to a date before the problem occurred.
Does it have an Nvidia graphics chip? (it may have an Nvidia sticker, or if not you can look up the specs of the model number. If it has, then maybe the laptop has a well documented fault, just Googling "nvidia graphics chip problem" will give you loads of hits. There's a forum here http://www.nvidiadefect.com/ that might help.
1st time I saw it the screen was crazed and it switched off. Started-up again in safe mode and again it turned itself off. Removed and re-attached battery and tried again that time screen was ok but after say 30 secs into boot sequence it shut down again.
EH ^ Where on earth have you got the idea from that HP laptops show error codes with lines on the screen?
The two main things that would cause a laptop to shut down again pretty much straight away are serious overheating (which would require the heatsink to have come unattached from the CPU for it to happen that fast) or it's got no power, so possible dead power supply.