I guess this post is a duplicate to your other post on Yocto flashing?
Regarding your issue about the first letter missing - I think this is just how it works. For me (on a Mac before my Edison broke) I had to press enter first to kind of register that I was there, then I could type in the commands happily.
As for why reboot ota isn't working - no idea I'm afraid, however as someone who is now quite versed at flashing an Edison without access to screen or wifi try these instructions:Re: How to recover Edison firmware
They're for mac, but they should apply to ubuntu fine.