My laptop (Win 7, Toshiba Satellite - C850D-11Q) is having issues with booting up.

If I try to boot normally the screen appears to turn on for 1-2 seconds, then off again and loops like this continually. If I try to boot from DVD, its the same. The laptop is in a loop, as opposed to the screen not working, as I can enter the BIOS after it has restarted as described.

I can enter startup disk, but unfortunately if I try to boot by USB I remain in the bootup loop.

Due to the above I can run any diagnostic checks using DVD/USB and there does not appear to be any built in checks built into the BIOS.

I've removed the HDD, checked using Disk Utility on OSX, and it appears to be fine.

I can boot into BIOS as normal. Which would suggest that the screen isn't the issue.

Any advice as to what the issue may be would be greatly appreciated.

Many thanks


UPDATE: Followed PIMP_JUICE_IT suggestions, checked for damage, cleaned out dust, removed HDD/RAM,

As Big Chris suggested I tried removing and replacing the thermal paste, cleaned fan/radiator, but unfortunately the problem remained.

  • 2
    Have you run any kind of memory or built in diagnostics? Commented Sep 3, 2016 at 12:46
  • 1
    Go into BIOS and reset all defaults and make sure it sees the HD and run an HD test from there if one is available. Consider cracking open the enclosure of the laptop and inspecting for visual damage or heat checks, swollen capacitors, etc. Be sure you'd blown out the enclosure with compressed air too in case dust is restricting air flow causing overheat damage and/or issues. Take the HD out and see if the DVD or CD or USB will boot from there. Same with memory module, remove and reboot and see if it'll boot with one or the other, reseat he modules as well as the HD... quick ideas... Commented Sep 3, 2016 at 19:20
  • Did the PC ever work properly with Win 7, or is this a new install? Commented Sep 5, 2016 at 6:07
  • Did you try to start the system without the graphic environment or "in safe mode"? If I've to guess I pick the video card, or its driver. You may try to boot via USB with a different system with and without graphic environment. If starts with Linux and not with Windows it is not an hardware issue (look in drivers & settings). If it doesn't start in any way it should be an hardware or a Bios settings issue. If it starts only without graphic environment in both system it should be again an hardware issue... There are even diagnostic systems that boot from USB that should make tests for you.
    – Hastur
    Commented Sep 5, 2016 at 6:22
  • 1
    If this doesn't work then it may be worth taking it to a specialist as the thermal paste may have dried up/cracked and is no longer transferring the heat from the CPU efficiently enough to the heatsink. This will cause the CPU to turn on then quickly off as it will have reached it's safety cut-off temperature.
    – Kinnectus
    Commented Sep 5, 2016 at 9:49

1 Answer 1


Apologies, it appears to be a battery issue. I removed the battery and the laptop boots up fine. I can't confirm that it is completely the battery at this stage, as I haven't used a replacement, but it appears to be looking very likely.

I completely overlooked this, as it booted up into the bios fine. I assumed that this wouldn't have been causing the issue as it would have prevented the bios from booting up fine also.

Hope this may be of some benefit for anybody else in the same predicament.

Also, the following question that I recently found after I asked the above question is also helpful:

How to Diagnose a Pre-Operating System Load or Hardware Issue

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