Também estou exatamente com os mesmos problemas.
Was this ever resolved? Mine just started showing -5°C all the time and when turned on, altitude counts down from 20000 metres. Barometer vents are not blocked. I've tried hard and soft resets, formatting, clearing holes, washing in warm soapy water (all tips from this forum). I can tell the hole is not blocked. One day it worked fine (dry). Three days later it didn't work fine (dry). So it failed whilst switched off?!!!!!
Was this ever resolved? Mine just started showing -5°C all the time and when turned on, altitude counts down from 20000 metres. Barometer vents are not blocked. I've tried hard and soft resets, formatting, clearing holes, washing in warm soapy water (all tips from this forum). I can tell the hole is not blocked. One day it worked fine (dry). Three days later it didn't work fine (dry). So it failed whilst switched off?!!!!!
It is a conspiracy to make us buy new hardware, my 520 (otherwise perfect) has also just recently started doing this, Rang Garmin support, they say it is a hardware fault with the chip / component that does both temperature and elevation, can't be repaired. They said to contact the "out of warranty" refurbishment number for my region and I might be able (if any are still available) to buy a refurbished unit for about 25-35% of the old recommended retail price.(and return the current unit to them)