I have the same problem. Green light flashing after connecting to power. No visible leaks from the supercapacitor and measures 3 V over it, so it seems to be working. Ai suggested it was the power supply bord 24 secondary area, so I had the row of capacitors changed, but no fix. Before I could turn it on, but now screen is black. Any suggestions are welcome. I am in my summerhouse in Spain so not as easy to fix here as back in Denmark.
