Chromebook Seems dead

I have 3 Chromebooks:
(all three are: HP Chromebook 14 G5)

I wanted to get them working with Ubuntu for my children.

For the first two everything worked perfectly:

I used Mr. Chromebook’s firmware

Disconnected the battery to run the second option for full ROM or whatever it is

Then followed the script restarting with the Ubuntu live drive

then installed ubuntu

and found a solution for the audio issue, leaving me with a working ubuntu computer with audio working.

I did this twice.

The final time I was doing this I think there may have been a loss of power at the point I was flashing the firmware.

Now nothing will turn on. Occationally, I can get some flashes out of the little blue LED on the side.

How can I recover this machine? I think that, once I get the screen working again and a terminal/shell open I will be able to do what I did with the other two. But currently nothing is working at all.

I don’t really want to buy additional hardware if I can get away without it.

Please help.