I followed this utube video
and fixed mine for under $10…and have a spare speaker (ordered 2 just in case).
There is a thread on the nissanhelp.com forum website that tells you how to extract the codes by holding the pushing the button at certain times. I tried it and it worked…The most useful part of that was being able to reset the backup alarm system so there are no stored codes after the fix. Search for “rear sonar” over there and you’ll find a post by baseballfanz that provides all the details.