Most likely the power supply is failing. Although you see some LED activity, there may not be sufficient power for the unit to operate correctly. See the many other posts on this forum related to power supplies.
You can try a couple of things. If you have access to a volt meter, try to measure the supply voltage while the unit is connected (use the meter probes to slightly pierce the insulation of the wires from the adaptor). It should be about 9 volts for an M1000 with removable end caps.
If it is nowhere near 9 volts, the perhaps you have another supply that you could use? Check voltage and current rating first. The voltage needs to be about 9, and the current rating at least 1.5 amps (more amps is OK). Center contact on the plug must be positive. Roku do sell spare supplies, and if you are in the US then the postage cost is reasonable. If not in the US, then the postage cost is outrageous (in my opinion), and you should look elsewhere for a supply.
If the supply measures OK with the SoundBridge connected, then there is probably an internal fault. Your unit will probably be repairable but needs suitable knowledge and technique. A couple of forum members, burkhardi (in the US) and g0pkh (in the UK) have repaired many units for people.
Hope this helps you,
Roku M1000, M1001, M2000, R1000, Roberts WM-201, Stream 83i