The common error is
ORA-19815: WARNING: db_recovery_file_dest_size of 214748364800 bytes is 100.00% used, and has 0 remaining bytes available.
You can't use ALTER TABLE to change the parameter, because the DB won't start. So..
sqlplus / as sysdba
create pfile from spfile;
edit the parameter db_recovery_file_dest_size (make it bigger so that the DB can start, hopefully you still have enough disk space), then
create spfile from pfile;
Also, delete the contents of the FRA (via operating system) then do the following:
rman nocatalog target /
crosscheck archivelog all
delete expired archivelog all