You can try resetting the network settings using the OSD. I haven't heard of anyone re-flashing the firmware to the previous firmware.
DHCP-If a DHCP server exists in the network to which the projector is connected, the IP address will automatically be acquired when you select DHCP On. If DHCP is Off, manually set the IP Address, Subnet Mask, and Gateway. Use or to select the number of IP Address, Subnet Mask, and Gateway. Key in Enter to confirm each number and then use or to set the next item.
Automatically or manually assigns the IP address to the projector connected to the network.