Bathroom Waterproofing/Rotten wood problem

Hi everyone,
Hope someone can help me with this; as you can see in the pic, one of my door trim situated near my shower was starting to rot at the bottom





Removed the panel and now left with this...





Was thinking of redoing the silicone Inside the shower screen and putting some silcone between the tile and the wall. You can see the membrane under the tile, which stops at the trim.





You can see in above pic that the silcone is not done Under the shower frame...



Hopefully someone can advise the best way to fix without having to redo the tile and membrane.

Cheers

1 Remove the post. The fixings may be badly corroded making dismantling impossible, in which case the post must be repaired in situ. With a screwdriver or similar tool, probe the timber to establish the extent of the decay. 2 Try to find a piece of wood of the same dimensions as the post you are repairing. Lay the damaged post and sawn off bottom piece on top of the replacement timber. 3 To make sure all the wood rot spores are eliminated from the decayed timber, stand the bottom of the post overnight in treatment fluid. Wearing gloves, treat the new piece of wood in the same manner and brush the solution on any adjacent woodwork. Wood boring beetles, their eggs and larvae will also be eradicated and timber will be protected against future infestation. 4 Apply a liberal amount of external wood glue to the bottom post and screw to the main post. To protect the screws from corrosion counterbore the holes and plug or fill flush with the surface. 5 Remove old weatherboard from door. The wood must be completely dry before tackling this repair. Apply wood treatment solution to the affected timber. Leave for at least 24 hours and brush on a generous application of wood hardener. Apply further coats if required. Allow to dry overnight and fill any cavities with wood filler. When dry rub smooth with abrasive paper. 6 Plug or fill the holes to cover the screw heads. Apply an undercoat and a top coat to ensure the new wood is well protected against the weather. Weatherboards and window sills have a drip groove on the underside to deflect rain. When applying paint take care not to brush excessive amounts on this area in case the groove becomes clogged up.