The firmware changelog is as follows (translated from Chinese, courtesy of Google Translate)
[update: I reformatted it, and fixed some wordings, hopefully making it slightly easier to read]
big display screen firmware
ZY1270 'large color' meter, dual USB female, green.
ZY1271 'flying dragon' meter, single USB female, dual Type-C port, red.
ZY1276 'large blue' meter, new fast charge trigger, blue.
V3.33-170613beta
solved a few calibration writing errors bug.
V3.33-170609beta
increased the screen display area,
optimized part of the page display,
optimized curve automatic range effect,
added ability to change to Chinese interface in the Language system settings,
optimized the System Settings display,
added 4-direction rotation in 3-parameter display page - long press to adjust.
V3.33-170618beta
added Serial Port Upload function,
simplified the Setup Menu by removing a few useless functions,
change some bugs.
V3.33-170622beta
fixed PD Listening mode current 0 bug,
optimized fast charge trigger interface automatically release fast charge,
optimized PD monitoring stability.
V3.33-170627beta
fixed off-screen does not calculate the capacity.
fixed the old version current display error during low temperature bug.
V3.33-170711beta
fixed minor interface garbled bug.
V3.33-170715beta
fixed Clear Record Data shows the error code 015 bug,
fixed high power parameter overflow bug.
V3.33-170726beta
added fast charge trigger direct operation on next power up
optimized possible PD flashing screen bug.
V3.33-170727beta
added support for the yellow ZY1273 to upgrade to this version.
V3.33-170730beta
added Huawei SCP-4.5V2A decoy trigger,
fixed Samsung AFC triggering stability.
V3.35C-171022
added E-Marker line test,
added Apple mFi line test,
added Apple 2.4A mode,
added PD Packet Capture details,
fixed PD3.0-PPS compatibility,
fixed D+ D- pull-up causing ip6518 bug,
optimized PD capture speed and PD trigger stability,
new automatic test shows PD maximum power function.
V3.35C-171023
solved a screen flashes after automatic blank screen bug.
V3.35C-171024
solved a factory test mode bug,
solved a PD trigger bug.
V3.35D-171102
optimized Auto-Detection Mode PD Power display compatibility
solved a PD history problem where misoperation may cause the device when unplugged not to return to 5V bug (PD bug has nothing to do with me).
V3.35E-171110
fixed Netease 65W charger PD Trigger blank screen does not work bug,
optimized the automatic protocol detection display order.
V3.35E-171117
added black gold ZY1275 support.
V3.35E-171120
PD interface screen and Automatic Detection interface screen now displays PD2.0 or PD3.0 protocol.
V3.35F-171129
optimized SCP trigger can output 4.5V5A constant current,
optimized the three-parameter display interface 12.5FPS high-speed refresh.
V3.35G-171211
fixed a calibration data lost flashing 0 can not start bug.
V3.35H-171221
added Samsung AFC 12V detection in automatic protocol detection,
optimized some AFC detection stability,
fixed automatic Protocol Detection PD power 100W display as 10W bug.
V3.35H-171224
solved a slow D+ D- curve wrong range bug.
Be careful not to flash incorrectly.
If the flash is wrong, please replace the -1 or -2 suffix and try to re-flash.
This version does not support DIY LOGO upgrade boot screen.