Fix reinstall brick #15
Don't run this unless you can recover from a brick.
Situation: user installs enso, then reinstalls 3.60 (which uninstalls enso but not the backup MBR), then runs enso app and selects uninstall. Result: brick.
This fixes it by always overwriting block 0 with a copy of block 0 which when enso is installed would redirect the reads to block 1 but not writes, and when enso is not installed would not do anything.
make a nand backup every time you reflash 3.60!