I don't recommend for anyone to do this.
I decided to disassemble my XL330S, because I want to add an eyebolt to the case so I can tether it to my motorcycle.
I used a knife to pry the bottom edge of the gray plastic case downward, which allowed the silver bezel lower edge to be popped up a little. This frees the tabs on the bottom of the bezel.
Then the bezel can be slid downward, to release the tabs on the sides and top.
I removed 4 phillips head screws.
Then I popped up the metal frame that holds the display assembly (it appears also to be part of the antenna). The grey rubber bushing stays behind on the display. It clips under two plastic tabs at the top.
Once the metal frame was out, I worked the display out.
The display is connected to the main board with a flexible conductor strip. The connector on the main board is latched by the light gray bracket. Here, it is in locked position, against the black connector body.
Here, the light gray locking bar has been slid away from the connector body (which looks almost gold in this photo, because of the reflection.) I used a small flat blade screwdriver to work each end loose.
The conductor strip is stuck down with double-sided tape. I was able to pull it up without kinking it too badly. Once the conductor strip is loose, it slides right out of the connector.
I removed three phillips head screws which were in the holes that look like donuts. Two on top, one near the bottom.
I popped the main board out, starting at the bottom. There is a locating pin near the USB connector that needed to be worked loose. Then I pulled the speaker and battery cables from their connectors on the main board.
There's the battery - it appears to be glued quite firmly in place.
Here's the front of the main board.
Here's the back of the main board.
So, here's the screw to hold the external clip I added. I used an 8-32 panhead stainless steel machine screw.And here's the external clip. I used a stainless lock nut and a washer on each side.
It's all back together... and it still works!