Quite possibly blown the gearbox on the S Class :'(
Oops.
Proper shagged? Or low fluid type shagged?
Harsh shifts from 2-3 which became not shifting past 2nd. No external leaks and only an 0894 code, trans slipping, suggesting a mechanical issue rather than an electrical one. Basically from first start, it seems normal but goes into limbo as it tries to shift from 2 into 3 and won't pick up any gear. Eventually it might change up, and then sticks in 4th. Turn it off and on again and it won't go past 2nd. It will run all the way to the redline in 2nd, but as that's barely 65/70mph it's of zero use on the road.
I have a service kit en route, and whilst it won't make it worse, it won't necessarily fix anything either but will allow the chance to inspect the gearbox sump for debris... Which will give a clear indication of the state of the internals.
Options are:
1. Try the fluid change and clean the solenoids but throw away ~£300 if it doesn't work. Possibly a temporary fix.
2. Source a known good transmission, service it and throw it in.
3. Replace the TCM and solenoids as part of the service and hope that fixes it. An £1,000 in parts and coding, but no additional labour.
4. A combination of 2 and 3.
5. Obtain a rebuilt/new trans.