Upgrade to Catalina stuck
My last upgrade before getting a new iMac since this one has still been working perfectly. Upgrading from Mohave to Catalina on iMac late 2013 i5 core 8 GB 1TB HDD. Seems stuck for at least 24 hours. Tried restarting in safe mode but still stuck on apple screen with progress bar about 40% across. Says estimating time remaining, but said will restart when finished installing before that. No response to control+L. At some point in the process is said 9 minutes remaining but that was maybe even yesterday. Not an experienced person in this matter. Have been researching online for hours and hours . Should I try an OS Recovery by shutting down, restarting and holding command+R?
iMac 21.5″, macOS 10.14