I have a Dell Inspring 7420 2-in-1 that is now about a year and a half old and in mint condition. (I couldn't add a product because the cursor keeps spinning.) For about a year, I've had a problem that the right arrow key will only work intermittently. I've contacted support and used Dell's hardware keyboard diagnositic in the BIOS and that registers perfectly. However, when I enter windows recovery and use command line, it doesn't work. The on screen keyboard works but not the physical key. Reboot into the bios to change settings, it often doesn't work. Go back to the diagnostic, that works. Reboot into windows, it may or may not work. Sometimes 15 minutes during using Windows, it starts to work.  This is a contradiction I cannot make sense from.

I was told that it's my fault - a software conflict. I've removed virtually all non-essentials in startup and that doesn't work consistently. I've deinstalled software that might have key combinations. Doesn't work. 

My mistake was trying to troubleshoot and get frustrated at being told it's a software issue and not insist on replacing the entire laptop, which diagnostically checks out. The 'support period' lapsed during this escapade and Dell has a ~40% as a 'reinstatement fee' which makes that cost and self-repair infeasible (as used machines appear on ebay for just twice this amount.) My hope is someone understands how this contradiction of hardware diagnostics saying it checks out but not working in the BIOS can be overcome or I'm just going to unload it and move to something else.