When I first installed the game I only had the base game. I had a singed sim and had the repair the stereo again and they died. Well, I discovered the nraas mods and also got some expansions and stuff packs. However, now my active Sims can no longer do anything that would cause them to die. Example: when I try to repair something while singed I get a message that I can't repair while singed but my butler can and dies. Is there a way to fix it so my active sims can? I've recently installed Retuner trying to find a way. I was wanting to have ghosts of every death type in my family grave yard. I know I can force death but I wanted to do it my self.

I don't think I've ever seen that pop-up, but maybe someone else will recall a context that can happen.
Did you only add NRaas mods, or are there some others by other creators too? Does it work if you take out everything but the NRaas mods?

If not, a screenshot of the exact wording of the notification would be helpful to see if anyone recognises it as related to a certain occult type, age stage, etc that may be protected

At the time I discovered it I only had nraas mods. Next time I get into my game I'll see if I can get it to pop up. My Sims may be too handy though. My game is also through steam if that helps any.

One of the Handiness skill challenges is

Electrician
Electricians have repaired at least 10 electrical objects. The experience gained means they will never be electrocuted by an electrical object again.

A sim with that benefit technically wouldn't be able to get Singed from repairing to begin with, but if they got it from another source (like from being on fire) it's possible they get gated from repairs to protect them from the 100% electrocution chance.
If you see it again, feel free to let us know what context it happened in!