board: restyaboard.sh Install Script not working on ubuntu 16.04

I´m trying to update my restyaboard form 0.5.2. to 0.6.1

The restyaboard crashes after downloading it from https://github.com/RestyaPlatform/board/raw/master/restyaboard.sh to /tmp and execute it with:

./restyaboard.sh: 63: ./restyaboard.sh: Syntax error: Bad function name

After changing the function names from upgrade-0.3-0.4 to upgrade_0_3_0_4 and so on it crashes with

./restyaboard1.sh: 154: ./restyaboard1.sh: Syntax error: word unexpected (expecting ")")

I think #/bin/sh is the problem or did I miss here something?