Am thinking 1 or both handles are bent too far inwards .....
If you have a bench vise .... take the pruners apart .....then lay both handles on top of one another - and see if both have all the same bends, in the same place .....
If not, take the most bent handle .....note which way you need to bend the handle outwards ....place blade end first into vise jaws - tighten vise down ... then using just hands & fingers try to bend a little at a time ....a soft-headed hammer might be helpful
Reassemble ....Then check to see if the jaws close ...
