Have industrial grade Lincoln at shop. VERY little experience with home boxes. Ones I've tinkered with were different. One's trigger only controlled feed mechanism, and the gun stayed "hot". The other was more like pro welder and trigger both turned on feed motor, and current to gun. If your box stays hot and trigger only controls feed it should be simple enough to come off of pos &neg legs to weld with a stick. If trigger shuts off current to legs also, you'd need to figure a way to bypass trigger.
Got a pair of jumper cables? Quickest way to give her a try without spending any money.
Bob