98 E300TD starter not disengaging

[Elasticmike]

Hi everyone

I have a 98 e300 td, a few weeks ago I started it outside my house to warm up before I traveled to work, after a few minutes the engine stalled, long story short the starter had burnt out as it hadn't disengaged (at that point I hadn't realised that's what caused it)
So, fitted a new starter, then same happened again.

Ive done the following

New relay
New K40
EIS tested alo g with key and ESL, no issues.

What else could cause this issue?

Thanks