Hello guys I need help

My dad's 2005 X5 was low on battery, I tried to start up the engine (few times) it failed and reduced the battery even more. So I took it out and charged it over night at home.

Returning the battery back the remote key buttons unlock, lock, or backdoor open don't work. But what worse is when I put the key into the ignition hole I can only turn it 1 step. (Can't cycle it to try to startup the engine) and there is no dash lights or radio turned on.

Any ideas? The car doesn't recognize the key? Or it's something else?

p.s there is non standrat added alarm system in the car as well if this makes any difference (Gps tracking, Voltage monitor etc..)

Thank you!

Yes the aftermarket alarm will make a difference but your main issue is that the key will need reprogramming to the car...

Usually the ECU will remember the key's serial however, the battery has been removed for a prolonged period and has defaulted the cars settings hence having to reprogram... Search the forum for "reprogram" HTH ;)