The tutorial you mentioned lists some good troubleshooting steps, however in this case I think this was your issue
It’s a risk everytime someone performs a hard shutdown or reset, but even more so while updating.
A safer method is to use REISUB/REISUO:
It does need some configuring before you can use it, but it’s well worth the effort.
Try this tutorial instead. 
As the title suggests, it’s written for just this type of situation.
If yours is a new installation and you opted to use a BTRFS (default filesystem on new ISO’s since Manjaro 25.0) then make sure to use the correct method to enter a chroot environment (examples are given in the tutorial).
Important: Please note that the manjaro-chroot -a command will not work properly with a BTRFS filesystem.
I hope this helps.
Regards.
Welcome to the Manjaro community
As a new or infrequent forum user, please take some time to familiarise yourself with Forum requirements, and the many ways to use the forum to your benefit:
Update Announcements
The Update Announcements contain important information and a Known Issues and Solutions section that should generally be checked before posting a request for support.
System Information
While information from *-fetch type apps might be fine for someone wishing to buy your computer, for Support purposes it’s better to ask your system directly;
Output of the inxi command with appropriate parameters will achieve this (naturally, formatted according to forum guidelines) and will generally be more useful for those wishing to help:
inxi --filter --verbosity=8
or the short form:
inxi -zv8
- inxi man pages (Arch Manual)
Be prepared to provide output from other commands whenever asked. It’s equally important to provide as much actionable information as possible in your first post, rather than simply indicating there is a problem.