Q:

Laptop won't boot to BIOS

I have an Acer Aspire 5943G laptop running Windows 10 which I turned on today and noticed the HDMI cable to the TV was still plugged in, so I pulled it out a couple seconds after I pushed the power button to the laptop and then it didn't boot.
Now if I try to boot up normally the same thing happens each time: The fan turns on, the LEDs all start to blink as per normal, I see a solid white dash at the top left of the screen and then a 3-4 seconds later the machine powers itself off and then back on again, repeating this process constantly until I remove the battery and AC cable.
The BIOS is called InsydeH20 and is running on v1.15 which at the time of writing is the latest version. After looking online at multiple guides, I tried to flash the BIOS with a USB stick by first removing the battery and AC cable, then - with Fn + Esc held down - re-inserting the power cable and pushing the power button. I thought this worked because the power stayed on and the USB stick's LED indicator flashed for a while as if data was being read from it, but the machine didn't auto shutdown which according to the guides I read is the signal that the flash is complete. I left it running for about 10 minutes then unplugged the AC cable again.
I tried booting up again and it worked, I logged in to Windows and was able to use the machine as normal. I unplugged the HDMI cable, went to my display settings to detect displays to make sure the system didn't think the TV was still connected and restarted again to make sure it was fixed, but then it wouldn't boot again and went through the exact same process as before, rebooting itself every few seconds.
The only way I can get the machine to boot now is by going through this process each time:

Unplug all power
Insert USB stick with BIOS update on it
Hold down Fn + Esc, plug in AC cable and boot.
Allow BIOS recovery utility to read the USB stick (doesn't actually update anything)
When USB stick LED indicator stops flashing, unplug AC cable and USB stick
Plug AC cable back in and boot as normal

If I try the process without the USB stick inserted it doesn't work
Is it possible this was caused by me pulling out the HDMI cable? I don't see how because when the machine boots up correctly after the steps above I can use the HDMI cable to the TV as normal and both displays work.
How can I fix this so I can boot the machine normally again?

A:

I figured out what was causing this and although I'm not sure of the why, I'm posting this as an answer because the issue is now resolved.
The issue was caused by a cheap wireless mouse which I purchased from eBay, more specifically its USB receiver. With the USB receiver unplugged the system boots into the BIOS and then into Windows successfully every time. Once Windows has booted I can plug the receiver back in and use the mouse as normal, I just need to remember to unplug it before I shut down.
I have no idea why booting the system into the BIOS recovery utility and then booting as normal bypassed the issue, perhaps it had something to do with the BIOS recovery utility trying to read data from the USB receiver.
The moral of the story is: if you're having issues with booting try removing any peripherals which aren't necessary for the machine to boot.

