Problem YES but not big at all as you can fix it yourself with the good informations.
Here you go http://kronometric.org/article/eta/eta_keyless_assy.html
Of course you'll have to first remove the date wheel if your movement have one and you're ready to go.
I've never worked on 2846s (only 2836s and 2834s) but I've read somewhere here that some of those have hacking function.
If your movement was hacking (before you screwed the keyless works of course) then take care of placing the hacking lever in the clutch groove before putting everything back.
If you don't remember just have look at the balance side of the movement and check if there is a tiny lever close to the balance wheel ... if not so your movement wasn't hacking andyou can skip that step.
Feel free to ask if you need some help
EDIT :
BTW ... is your movement a 2836 or 2846 ? cause sometimes you write 36 and sometimes 46
Nevertheless 36 or 46, and A or ETA, the link above wil be usefull to fix your keyless works.
One usefull thing your sould do, before putting the setting lever on, is to lubricate a little the hole on the movement plate where the setting lever's pin goes ... doing that way you'll be certain that the pin will come back to place after pushing on it to remove the stem.
Another usefull thing you could do is to put some grease on the "squared" part of the stem before putting it back on, then turn it both ways while putting it back, so that the square part of the stem can be aligned with the square hole on the wheel