The RH sensor doesn't seem to work well...

Hi,

I bought a 1 year old used DDR583R that wasn't used for most of the last year. The woman told me that it was working well. before.
I notice that the RH sensor displayed on the LCD 2% of RH!! I'm not an engineer but I know that is impossible in Eastern Canada. So to be sure, I bought an hygrometer. I read 70% RH. The only way to make the dehumidifier working is to turn it on continuously.

Is there a way to fix the RH sensor problem?

Thank you
Nick

PS: I also noticed a weird smell kind of burning dust.