I shorted a battery carrier by accident, and the springs got too hot instantly, and shrank.
They lost their flexibility somehow.
When I try to bend them back, and I insert a battery, they don’t bounce back when I remove the battery.
Is there a way to get the springiness back?
I can just replace them, but I was wondering for the sake of an interesting topic, if it would be doable to get their original quality back.
No.
To elaborate on Sammy’s point, the heating of the metal has made it lose its temper. Whilst it is technically possible to retemper the springs, it would require a precisely controlled heating and cooling process that is likely prohibitively difficult
Yup, what @merlot ^^^^^^^^ said.
You would need to know rather closesly what the base metal the springs are made of is, then some numbers for tempering… the heating and hardening would be easy. Tempering to springs again would be a real pain, even with adequate temperature guide, with such small parts. And any platting on the springs would burn off in the process too, changing corrosion characteristics, visual appeal, and as far as I know, conductivity, if that ever mattered.
I’ve made back springs for folding knives, and its a tedious exacting process to get spring temper just right between brittle and soft. Not worth it on replaceable parts, unless its something you Really Really want to learn to do.
Out of curriosity, what are you using for a battery carrier, that has springs? 
Thanks so much for the comments guys…
Good to know, and I think I had read it somewhere but couldn’t find it.
Now looking for other springs