Did this happen after the transmission was checked? There is a backup light switch on the transmission which could have failed. Do this. First, check fuses 59 and 63 in the under-hood fuse box. If the fuses are good, confirm they have power. Here is a link you may find helpful:
If everything checks good, I need you to go to the transmission and locate the switch. There are two different manual transmissions used. I attached a pic of both showing where the switch is located. Make sure the connector is tight, clean, and not damaged.
If everything is in good condition, disconnect the connector. Using a test light, probe the connectors, one at a time. One should have battery voltage.
The last pic shows the fuses to check.
Let me know what you find or if you have questions.
See pics below.
Images (Click to enlarge)
Monday, May 30th, 2022 AT 9:17 PM