I’m sorry to hear that. We cannot speak to other companies’ policies or reasons they may object, but I can say that we share your belief that a system you fully own is yours to control. suretyDIY uses no long term contacts, and all system programming and installation features are open to the user.
A couple things to verify:
If you have the current installer code, you should be able to access while all partitions are disarmed. Make sure that all partitions are disarmed when you try to access.
You can jump partitions and then check arming and disarm with 8 - installer - 6 - partition number (there are 6 partitions, so 2, then check 3, then 4, etc.)
There shouldn’t be any full programming lockout option on the Concord 4, however the NX panel does have this option. Can you confirm you have a Concord 4 and not a Networx panel?
If all else fails and you swapped the keypad while the system was powered, you will want to fully power cycle the panel (should try a power cycle anyway). Unplug the AC transformer, then battery. Wait a few minutes, then plug in the battery followed by the transformer. Any luck?