This article is to diagnose a healthy android display.

The following tests assume that everything besides the display is powered on. If not check out Communication/Power Issues.

Make sure the tablet has a charge.Leave the tablet charging for 30 minutes (preferably through a wall charger).
Check that the small round pin power cable is plugged in and the micro-USB cable is plugged into the 'Host' port (not 'USB').Plug them in.
Check that there is a little lightning bolt indicating charging is occurring in the top right of the screen inside the battery symbol.If the hub PW2 light is a constant red, but the tablet is not charging, then the hub and tablet need to be sent in or each is available for purchase to further diagnose the problem (ie. get a new hub and see if it fixes the problem).

If the hub PW2 light is not on and the tablet is not charging or communicating, then the hub is likely the problem. A replacement can be purchased.

If the PW1 light is not on, try plugging another device with a female micro-USB port on it. If the PW1 light comes on, then the tablet needs to be replaced. In general, the hub is the problem, but the tablet may be.
If you have a little black hub behind the tablet, 
  • check that the PW2 red light is on.
  • check that the PW1 red light is on.
Check that the cable is good running from the little black hub behind the tablet to your machine or robot.Replace the cable with one you know works, if you have one (many use a standard RJ-45 to RJ-45 cable which is the same as a standard Ethernet cable for internet connections).

If you have both the Perfect Stitch regulator and Butler robot that does not have a micro-USB port on it, you can take the cable that is plugged into your "Stitcher Box" port on your robot and plugged into the "Robot" port on your machine electronics and plug it into the "Remote" port on your robot and plug it directly into your little black hub behind your tablet. If your tablet can now communicate with the robot, then the cable is good, and the little black hub is also good, and something may be wrong with your PCB. Your PCB may need to be sent in.
No FTDI error shows. and micro-USB port is active.If an FTDI error does show, then most likely, the device has put the micro-USB port "to sleep" and by unplugging the micro-USB on the tablet and plugging it back in will solve this issue. This happens when the tablet turns on when the micro-USB port is occupied.
The app has been closed completely and restarted.Restart the app by pressing the square or two overlapping rectangles at the very bottom of your screen then swipe off Perfect Stitch or press the 'X' to close it completely. Then go to the android home screen and tap the Perfect Stitch icon to open the app again.

Tests for the Linux display

Either it powers on and works, or it doesn't.

How to Send in My Product for Repair

If all those tests pass and are behaving normally, you can positively say your display system is working as intended.

If your machine is still having problems, then we recommend doing more field tests to identify what to do to get your machine working as soon as possible.