Does anyone recognise this e-bike display unit

I have a Batec "bike" that fits on the front of a lightweight manual wheelchair as seen in link below.

https://batec-mobility.com/en/products/handbikes/batec-scrambler-en

I am wondering who made the display?? (I doubt it is batec as they seem to just buy the electronics in and stick their name on it).

The reason I ask is...

It came with no instruction on the display. Pushing both buttons together seems to get into a menu... firstly "c1631" which the numbers can be adjusted. I assume this is to do with the circumference of the wheelsize as I guess 1631 is typical for a wide 20" tyre"

The next menu you can change KM/HR to Mph/hr. I want the latter, but it seems to revert back to km/hr everytime I switch it on again. I guess I am not storing the change in settings correctly

The last menu is confusing as it says on one line "-0.1" and on the next it says "527" and a picture of a battery. When the motor is running this figure drops to around 400 and then returns to 533 again when motor is stopped. Is this something to do with charge in the battery?

Also it is possible to toggle the "-0.1" figure to 0 and above in 0.1 increments. When you do this the bottom "527" reading increases by 1 unit everytime I increase the top reading by 0.1. All very strange. I have posted a picture of this screen and the "527" seems to fall with increasing use. What is the idea of being able to toggle the 0.1increments ?

Anyone can help?

AFAICR from what was researched for this thread
https://endless-sphere.com/forums/viewtopic.php?f=2&t=105375&hilit=batec
(which has the most info about the system), Batec seems to have had made for them the system as a whole--couldn't find any other vendors of the same parts.

Why it doesn't save the setting, I don't know--Batec would have to answer that. My guess is that at least some settings in the display don't actually write to the flash memory; the default settings for those are protected against "user error".

Regarding the last, based on the info you provided, it's probably the battery level meter settings, and the number decreasing under load is showing voltage sag. The incrementable number is likely a calibration setting either for the current shunt or for the voltage meter.

The "527" may be 52.7 volts, as that is near what a 48 volt battery would read with an almost full charge. If it sags to 40 volts, though, you likely have a damaged battery - again, assuming that it's a voltage display.