Never handle ANY electronic devices WITHOUT
wearing your (ESD
) anti-static wrist-straps... EVER!
It could be more damaging than a cesspool would ever hope.
If you are not adverse to purchasing from eBay: China sources there (free shipping) sell cases, screens batteries up-to whole un-locked GSM phones for under $20...
Having no personal knowledge of the NOKIA 2700 motherboard... I am just assuming that it is a multi-layered board (not actually suited to solder/trace repair.
I believe board replacement would be cheaper... and since I am seeing NEW PRODUCTS (with free shipping from China... my opinion (with extensive back-ground in water-recovery of electronic devices... ...Minutes & hours is possible IF ALL POWER IS IMMEDIATELY REMOVED
... immediately field stripped into smallest components, contaminants removed (washed)...
for DAYS... you MIGHT have something worth saving...
Untreated for Days... and as you said "WEEKS
" you are assured to have corrosion, electrolysis & galvanic tinseling on the PCBs alone...
Connectors, batteries, switches, jacks and $4 displays are simply not worth the effort...
Whole-phones on eBay.
If you think you want to TRY to save your SIM Card...
wipe it completely clean with a 90% isopropyl MOISTENED (only: soft/clean) cloth. Take a SOFT
(graphite) pencil and gently (smoothly) draw on each contact completely.
Repeat the 90% isopropyl MOISTENED (only: clean) cloth wipe down and let it dry.
Take a clean toothpick and put a (NEARLY invisible) SPECK
of white lithium grease on each
Wipe it all off with a clean cloth... You are now free to TRY
to use your OLD SIM
card under your new contacts (keeping in mind that SIM has been WELL beyond any/all design considerations
... and can damage its NEW host)... I'm just saying.