Could be a number of things: immobiliser, fuel pump, fuel pump relay or the lean angle cut-off switch? You'll have to test each component one at a time and see if you can isolate the problem. Has the bike been on it's side? What's the immobiliser LED doing/showing? Is the engine trouble warning lamp lit or perhaps flashing when you press the starter?

More often than not the error Er-04 (ECU-dash communication) is a broken/abraded wire or a dodgy connection. There are obviously several strange things going on here. It's odd that the temperature warning light would be illuminated, unless the sensor is stuck in the closed position or there is a short in the wiring, either way that in itself shouldn't cause it to be a non-starter.

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