Please try the following combinations one at the time - one will have to give you the Android System Recovery menu or the triangle with an exclamation mark inside.
1. With the Metro 2 in off mode - Power button + Volume down
2. With the Metro 2 in off mode - Power button + Volume Up + Volume down
3. With the Metro 2 in off mode - Power button + Volume Up (if you had not tried it yet)
Please kindly comment below as you get along