Best guess is that the TWRP you loaded was not built for the One Mini. Can you post a link to where you got it from? It could possibly be a bad download, so do check if an md5 code was provided, but don't flash again unless you are sure it's for the One Mini rather than the One, for example.
A factory reset just deletes user data, so won't help. What you need is a compatible recovery. So if we can't find a recovery for you then a ROM Update Utility would fix it (but erase the phone and put you back to where you started). If you could extract the recovery image from one you could flash that alone though.
I'm on my phone ATM so not best placed to look for this stuff. Will be back later if nobody has found the stuff in the meanwhile.
Meanwhile I have posted the suggestion that we add a One Mini forum