Question about key programming

I have a 2006 camry. Lost one of 2 master keys. Nowhere
near my dad who has the other. That time I followed a
YouTube video to program using the original master key.

The fob stoppef working today it was fine earlier in the day.
I replaced the battery.
Trunk opens. Unlock and lock button makes sound but
doesn't do anything. Dashboard lights up but no radio.

Does it make sense id have to reprogram just because
battery inside the fob dies? I followed a youtube video but it
didnt work. The guy was focusing on adding a new key but
said if you lost your prev keys you can removes the old
entrkes and reprogram by turning on/off twice instead of
once to add on.... can someone help?

Nowhere near my dad who has the other master key.
2006 camry