After a mouth on the shelve my OSD stopped working. I took out the micro minimOSD, updated the firmware and everything works...
But the charset is messed up.
So I used MWOSD configurator V18.104.22.168 and connected the board, selected the standard font and clicked Upload, waited until it finished and nothing changed.
As far as I understand the charset is stored in the EEPROM of the MAX7456. So I looked at the datasheet and made sure to power it with more than 4.75V. But nothing changed, still can't change the font.