Never attempt a firmware upgrade over Wi-Fi. Use an Ethernet cable to connect your computer to one of the router's LAN ports. How to Install DSL-2740U Firmware Version ME 1.04
Only download ME 1.04 if it is explicitly listed as compatible with your H/W revision. For example, some 1.04 versions are strictly for Hardware Revision A1 . dsl-2740u firmware version me 1.04 download
Look at the label on the bottom of your router. Look for the string "H/W Ver." (e.g., A1, V1, V2, or C5). Never attempt a firmware upgrade over Wi-Fi