Resolved! Wrong value of VCAP capacitors in STM32F407VGT board
I have 10uF (=10uF+100nF)ceramic capacitors for VCAPs in a custom board. Voltage there is 2.7V. Supply voltage is 3.3VI have problems getting the STlink to accept the board. First I managed to erase the chip, now STLink does not even recognise the c...