PC cannot be started at all

I cannot restart my Windows 10 TabletPC. It was working fine until I returned to it after a few hours. Now when I press the power button, the green light turns red which is the the usual sign it is starting up. But nothing happens except the light turns green again, no other sign of life. I have tried my two 2 bootable USB Flash Drives, which normally get the PC going in this situation, but so far there is no response.

I am having to use an old Android Tablet to send this. It is the first timei have accessed the 10 Forum via Android

What power supply is used when the problem occurs, battery or AC or on either ?

Thankyou for your responses, all of which I would have followed up where it not for the fact that the problem is solved. I will bear them in mind if it returns. I am still using the Android Tablet but the PC is working normally now, though I do not know why. I had used "my special technique", ie. messing about with everying I could for a few more hours without having a clue what I was doing, followed by leaving the computer alone for several hours over night. In the morning it woke up, right away.