I can't exactly recall, but if memory serves, the unit still communicated to my laptop even though the display was off.
Maybe try leaving the laptop connected and then turning the unit on. Also try switching the unit's on/off switch. You're looking for the laptop to detect the comms port of the...
If anyone stumbles across this thread, the correct firmware for the SPF 3000 TL HVM 24 will likely start with F28035. Also, be sure to ask Growatt support for the correct firmware.