I hate to say it...
buuuutttt..
I really dislike the state of droid tablets and phones...
suuuurrre...
there is plenty to read up online to fix a samsung for example...
but little for odd models...
I do feel your pain...
Not too long ago now (a week or 2 I think...)
I was handed a alcatel one touch pixi3 ...
it was internally ...a mess..I couldn't get past the start screen initially...it was sooo bad...
There is little in the way of anything on the web concerning the model...
let alone about freeing it from malware ...
I am not very droid savvy but I did manage to erase all the partitions where crap could (and was) hiding ....and get it back to a proper clean state...
Between the touchscreen (oooohhh I hate capacitive touch with wee itty bitty onscreen buttons...) ...the joy of a handheld smartdevice that needs antimalware, antiviralware, etc...
I am soooo content with my maemo....
Reflashing may or may not have any affect.
Didn't work for me...
I know I had to burn out every partition there was to get rid of it...
It could be that your malware is hiding out in an ordinarily inaccessible area or partition like where the frp resides...and so you can't get at it by normal methods...but have to be a bit more severe and burn out the bloody cockroaches...
Don't let it multiply to other areas or hide itself...
Burn!
Burn!
https://www.youtube.com/watch?v=sglyFwTjfDU