@albertmarshall that is the age old problem with not having backups. There is no way you get the data of your phone unless you get the phone to start up. Transplanting or replacing the memory IC will not recover your data.
You need to determine where the error is. Something like this "revoking the processor maybe" does not tell us much since we do not know what they did. Nor do we know what they have checked. Commonly a no power situation is related to either the charging board, a shorted battery or a torn flex that comes from the daughter board to the main circuit board. Check/replace those. Then check the voltage on your battery connector with the phone plugged in and without.
To replace the battery, use this guide [guide|146769] For the rest use [https://www.youtube.com/watch?v=1Tkmqn2fFMg|this video] Let us know what you find out.