We have tried different cards and power supplies. No effect. We can get to them through login with the original card and program, our program, which has some changes, being on a different card works only with 2 of the 4. The pi's should be the same.ThomasS wrote:It's quite unlikely that both are faulty. Have you tried different power supplies? Have you tried re-formatting the SD card or swapping SD cards with the other two, working Pi?