If your Trofa boots to a teal screen, it may be a sign of a disconnected bill validator or of disk corruption on the tablet.
Check that the all cables are fully connected inside the machine, including behind the door, on the USB hub to the right of the vault, and those of the bill validator within the vault. (Take great care when handling cabling, especially that of the bill validator harness located inside the vault.)
If all cable connections appear solid, and the teal screen continues to present after rebooting the tablet (holding down its power button for 7 seconds), then reflashing the tablet may resolve the issue.
Follow the article 'Reimaging the Trofa's Nexus tablet' to flash it the latest image.
If the teal screen continues, create a support ticket with details on the situation and the steps you've taken thus far.