Greg, K0RS had a great idea. If you don't want to do that, then call GigaParts. Tell them the story, and ask them if they want you to send the radio back to them, or get an RO and send it to kenwood. Maybe just maybe GigaParts can tell what is wrong ( I doubt it ). I assume you are the original owner, with a bill of sale, that has the serial number, date etc. Did you fill out the warranty card ?? Might see if it's OK to do that now.
Lots of good ideas posted here, and you seemed to have read the manual and tried a bunch of stuff, and it's still not working.
Time is running out for you. Companies like Kenwood and GigaParts are short of service people, support sales etc .. I bet if you go one day past that sales date or actually the received date, you will loose all chances of getting a free repair, or new rig ( slim chance ). Join the 890s user group and see if you can see that some people have had to pay for service and parts. It will hurt.
I think everyone reading your story feels sorry for you. But now, it's your choice. Wait to long and go past that one year mark and have no recourse and everyone will say, we told you so.
Your choice, best of luck.