Originally Posted by The Great Stonk
if its a 2 piece external BB unit you dont use a crank puller to remove the cranks. unless you have cranks im not familiar with.
With a title like "crank puller tool has threaded the inside of the crank", I think it's safe to assume it's a square-taper that DOES require a crank puller. Unless of course OP was using the crank puller to file his nails, of course.
The suggestion of re-boring + threading the crank-arm assumes that the cost of this operation plus a new, custom crank puller to service this now-unique crank-arm is cheaper than a new crank-arm.
2 reasonable options:
1. Put the now problematic crankarm back in place, and assume that your ability to service the BB will be quite limited from now on (which may be ok for a while), or
2. Replace the crank arm.
You can do #1 for a long while, and then later #2.