Pool thermometer IBS-P01 measures a far to high temperature

My pool thermometer IBD-P01 measures 50 degrees Celsius where the water was 10 degrees and displays this on the display and on my iPhone. I tried tot reset (I pushed the the buttons 5 sec. in all possible combinations) and took the batteries out and left them out for some houres. The temperature meassurement stays high. What can I do?

Please check if there is water in the transmitter?
If you put the transmitter indoors, open the lid and remove the battery to dry, and then install the battery to test, does it read accurately?
If the error is still there, please contact support@inkbird.com for after-sales.