Stuck in a boot loop

This tablet came installed with windows 8.1 which i successfully upgraded to windows 10. all was fine until it would not connect to my router using wifi.

I tried a refresh install of windows 10 but it gets to 79% then just stopped. I left it hoping that it would sort itself out but ran out of power. After a charge i now get a message "The computer restarted unexpectedly or encountered an unexpected error. Windows installation cannot proceed. To install windows click OK to restart computer, and then restart the installation."

Restart to same message!

Cheap tablet z3725 cpu, 1gb ram. SD card to 32gb.