Acer Iconia One 8 Service Manual page 42

LCD:
LCD test, many and different colors(W/B/R/G/B) be displayed to the screen, and then let you choose which color do you see on
screen finally, RED or GREEN or BLUE,
G sensor (calibration) & G sensor verification:

Enter the Manual UI Test in factory image mode

Put Citizen at horizontal balance jig

Press G sensor to calibration, and check Pass result message
This example may get PASS when choose "GREEN".