from install_amp, line 722:
outn("Configuring install for your environment..");
if (!$dryrun) {
       exec("chmod u+x ".$amp_conf["AMPSBIN"]."/amportal");
       exec(dirname(__FILE__)."/apply_conf.sh");
}
out("OK");

it seems your amportal.conf does not contain the AMPSBIN line. This is
one of the upgrades from 1.0.009 to 1.0.010, which should be applied 25
lines bellow, in line 750 of the same file. Nice... you found a nice bug
in the upgrade script. Feel free to file a bug report.

To fix it, be sure that /usr/bin/apply_conf.sh is available and add to
your /etc/amportal.conf this line
AMPSBIN=/usr/sbin

and then execute the upgrade script again. That "should" work, but who
knows... :)

Do tell us if this works or not.