Hi, I’m Louie. Sorry you had to wait awhile but I’ll do my best to help.Initially, have you tried unplugging the RC689D for an extended period of time ? ....and then plugging back in but into another outlet ?
Then it would be an internal hardware issue.
Are you then considering a DIY (do-it-yourself) repair approach? If yes, do you have access to and familiar with a multi-meter (and even perhaps a soldering iron)?
I realize that the above information may perhaps be not what was expected. Unfortunately, there is no quick-n-easy fix and neither is there a workaround; sorry for having to be the bearer of bad news.
Still and if of interest, consider manually cleaning the lens. This would serve as both an attempt of a fix and as a test. If the cleaning is not corrective, then there are other faults requiring major repairs. Please click HERE to serve as general reference.