I power the laptop on and the Dell logo is there with a blue bar at the bottom of the screen slowly moving left to right. When it has filled up the block, the screen flashes to a black screen with small white writing at the top and very quickly back to the Dell logo and thereafter flashes between the 2 screens.
If I power off and restart, the flashing continues. If I wait an hour or so, it starts again with the Dell logo and bar beneath slowly filling up and then continues with the flashing alternating screens.
I have tried removing and replacing the battery.
I have hit F12 and gone through all the diagnostics but there are no error codes.
I am running Windows 7 and do hope this is not caused by my inadvertently clicking on a Windows 10 popup!
Any advice gratefully received.