The TFT screen on the HalloWing can become un-adhered if it is bumped or wiggled too much (or left in a very hot Jeep near the windshield in the hot southern California sun, for a totally hypothetical example that didn't necessarily happen to the author). Fixing this is pretty easy -- you can use double-stick tape, E6000 glue, or Sugru to fix it back in place. Here are some action photos of these fixes.
Double Stick Tape
Cut three thin slices of double stick tape, then place them around the edges of the backlight.
Press the screen down and hold for a few seconds to adhere.
This is strong glue and is even better than tape if you plan to leave the HalloWing screen exposed on a costume without the lens and cover.
Use a toothpick or skewer to place small dabs of the glue around the perimeter of the backlight.
Press the screen down and hold for a few seconds, then allow to cure overnight.
You can go all out and create a protective frame using Sugru moldable silicone rubber.
Open a sachet of Sugru and tear off a small ball of it.
Roll the ball into a small cylinder and press up against one side of teh board and screen.
Repeat for the other side.
Allow Sugru to cure overnight.
Want to see some stats on your HalloWing? Double-click the board's reset button to get to bootloader mode, then drag the HallowWingM4_Diagnostics.UF2 onto the HALLOWBOOT drive!
This UF2 is for the Hallowing M4
If you have the Hallowing M0 use this UF2