Dintek U1560 (Aosiman ASM-156UC) - touchscreen not functional

[japlytic]

During operation of this unit, the touchscreen has stopped responding.

Here are the USB IDs which are used by this display:
27C0:0858 (which has disappeared but fortunately I obtained beforehand - touchscreen controller?)
1A40:0801 (Terminus Technology)
1A86:7523 (HL-340 USB-serial adapter)

Could it be an issue with the firmware?