My Moto G has constant error messages pop up. How can I solve it?

[AC Question]

Since last night my Moto G shows constant error messages such 'the process com.google.process.gapps has stopped' (most often), 'the - app has stopped', and a few others. Each time I click on 'OK' another one appears, so I can't do anything on the phone. I can access the Parameters but that's about it.

I tried some solutions I found on the internet (such as clearing the data of google apps?), I rebooted it several times, and also tried the Recovery mode but it says 'Boot up failed'...

Does anyone has an idea on how to solve this issue? Thanks in advance