Hello
Depending how hard and how you crashed, open phantom, under the top ( the GPS unit is located ) remove the GPS unit, inspect CERAMIC antenna , as they like to shatter in a decent crash. Might also require IMU calibration ( advanced preferably ), and after do a fresh compass calibration.
Did you download the assistants?
RC ASSISTANT
PC ASSISTANT
AND
WIN DRIVER
you must hook phantom to computer to calibrate IMU ( inertial measurement unit ) receives info from ( accelerometer, gyro, and compass ) takes all this info and makes a MOD VALUE ( MOD, is MODDUS, meaning absolute value )
So as you can see if anything is out of whack , you can experience ALL sorts of weird stuff. But I would open it up and inspect for anything damaged, unplugged, loose, broken solder joints, ect. If all looks good, hook to computer, turn it on, and run advanced IMU calibration ( ignore the IMU too hot crap ) they all do that, then outside for a fresh compass cal. See what happens?
If after all that , your still getting red light, than something is amiss somewhere? You'll have to look closer.
Hope this helps
J Dot
Ps the ceramic antenna is super easy to replace with minimal soldering skills and $8, buy the 4mm antenna, not stock 2mm, you'll get s stronger signal, i can supply part number here:
( part number on bottom of antenna )
View attachment 59138
Watch YouTube on correct way to open your phantom ( do not remove motor screws ) not that it matters, but you don't need to. Please let us know if we can help out more, and keep us updated!
Take care!
J Dot