I can see you are using a PSS image so I am assuming this is a PSS account instead of the SNTC. In the future you may pursue the PSS community as sometimes there may be a difference in resolution.
In any case
the 55 on the last line of the install log means 55% completed on Monday run that command again and verify if there is any significant improvement in percentage.. If there is or it is completed I would leave until completed. If it still at 55 , save your credentials and device list and reboot the box and when back on the admin shell do the command below:
admin#download sp-30.0.0-0-0-lnx64
and see if it does the job of downloading,
from 2.5.1.6 you cannot upgrade to 2.7.3 or 2.7.3.1 you must upgrade first to 2.7 main
so in any situation you must first use the below first
admin# apply sp-30.0.0-0-0-lnx64
as far as the user collectorlogin and the user root you will very likely need this since in many instances the upgrade of the CSPC from older versions to new versions may temporarily break the admin mini shell. all versions including 2.5 X has those logins but they are not set by default. I strong recommend you from the admin shell run the following commands below to get those accounts and passwords set
admin# pwdreset collectorlogin 90
admin# pwdreset root 90
additionally sudo will not be available as soon as you upgrade
