TVs often swith to AV1 automatically if the appliance is attached by scart to that input. I don't know if that is practical with regards to x-box, but several things like DVD, digibox etc will turn tv to AV themselves. Try using AV1 rather than AV2?
Losing a remote sucks, you might try finding an original replacement for your TV, from a site like www.remotecontrolhookup.com. Or you may have some success if you purchased a universal remote, but no guarantees there.