Take off the cover to your terminal block (where the plug wire connects) and use a multimeter to check for the correct voltage to the unit. Red to white and black to white should be 120vac. Black to red should be 240vac. Your L1 circuit (the black one) is dead so when you turn on one of the burners, the L2 circuit feeds into the L1 illuminating the display. It may be a loose connection at the block or inside the outlet. Sometimes it is the breaker that is bad. Try tripping them closed them back on a few times in case one has stuck open. Your range should work fine, one it has the proper voltage.

Glad I could help.