Even if a monolthic flash device isn’t visibly cracked there can still be internal damage. In electronics, all connected wires have a path to ground, using a multimeter we can measure voltage drop in diode mode to get a rough idea of the damage. Here we’re measuring the voltage drop on all 8 data lines, all the data lines should have the same value. If one of the data lines has a different voltage drop there is likely an internal problem with the monolithic chip preventing recovery. Using this trick can save you hours of troubleshooting why the monolithic media isn’t being recognized.
In this example, the bad SanDisk monolithic SD card had a value of 0.46 on all the data lines except data pin #3 which had a value of 0.67. The donor card had a value of 0.48.