Take off the back dust cover and put a cheap usb fan blowing air in there over night. Or a leaf blower if your impatient. Should dry up pretty good. Remember to put the seal back on before driving especially if very humid. Then check the dust cover or lense for cracks or splits and fix if you can. If persists, you might need to introduce more air flow. There are some ive seen that drill holes at bottom to let water out, but I've never done it...ymmv.