At this point I only have a couple things left to try. One is to turn everything on, wait for them to boot, then tap on the battery icon at the top left of the ST-16 screen to bring up the controls monitor. Items 7-8-9 and 10 are the camera controls. Cycle them to see if full range of motion occurs for each one, except one, which I think is channel 9. That one will only show half travel as the switch is a three position design that's only providing two functions. If they don't show full travel there's likely an issue in the ST-16 such as dirt or corrosion that needs to be cleaned/corrected. If they do show full function the problem is somewhere else.
The last idea, and something I have not personally tried, is to attempt using the Typhoon H GUI to try the camera CGO-2 calibration function to see if it will work with a CGO-4. The 920+ does not have a camera calibration feature the user can access and activate that I've come across.
From there I'd call Yuneec and have them check the serial number to determine if the 920 was new or refurb'd. Of course they would have to have records to establish that and want to tell you. FYI, your seller is one of two authorized sellers in Kansas City aside from Yuneec. One of them sells refurbs while the other sells Yuneec warehouse stock. I don't recall which is which. One member here does but he would have to provider further clarification. Vertigo Drones has been the lowest priced "store front" seller of the 920+ and they're still at $2,999.00 for new 920's. The $2,599.00 eBay pricing makes me wonder a little. All that doesn't really matter as the warranty is applicable as new or refurb.