<<1. I got following error reported Firebird-3.0.2.32703_0_Win32 :
"internal firebird consistency check (cannot find record back version (291), file: vio.cpp line: 4676)">>

Try a gbak using something like the following
gbak -b -v -i -g copy1.fdb{path}copy1a.fbk
using the –g switch to signify "no garbage collection"

If this succeeds then you can restore the database without the corrupt record pointer.

Paul