To my knowledge …
The LED-color codes for the A7 & A5 are similar.
A pulsing red LED, means that the A5/7 system is booting. If it continuous (‘hangs’) in this state, some error is preventing the boot-phase to successfully finish.
I have experienced that in most cases, the WiFi module is causing this error. I have tried to repair 2 of those WiFi modules, but it is very hard to diagnose.
But I have been successful by replacing the WiFi modules. Then the A5/7 worked properly again.
If you look for a replacement WiFi module, double check you are buying a working one. Once you have the speaker casing opened up, the replacement is a piece of cake.