I think I found a bug in v6 rev7:
In mobile/login.php line 98:
from
echo '<span style="float:left;">' . tep_draw_button(IMAGE_BUTTON_FORGOT_PASS, 'mail-closed', tep_mobile_link(FILENAME_PASSWORD_FORGOTTEN, '', 'SSL'), '') . '</span>' . '<span style="float:right;">' . tep_draw_button(IMAGE_BUTTON_LOGIN, 'key', null, '', 'SSL') . '</span></form>';
it should be
echo '<span style="float:left;">' . tep_draw_button(IMAGE_BUTTON_FORGOT_PASS, 'mail-closed', tep_mobile_link(FILENAME_PASSWORD_FORGOTTEN, '', 'SSL'), ''). '</span>' . '<span style="float:right;">' . tep_draw_button(IMAGE_BUTTON_LOGIN, 'key', null, ''). '</span></form>';
otherwise is throws an illegal string offset 'type' error