mount /dev/sda1 -o rw,remount
Now that the drive is in read-write again (test with a simple touch /tmp/test), continue the installation with this:
dpkg --configure -a]]>
For those having the same problem, this is where I found the solution you see below.
$ sudo sdparm --clear STANDBY -6 /dev/sdb # note that your device could be something else, for example - /dev/sd<something>
And if you get an error, something like this:
change_mode_page: failed fetching page: Power condition
Then you should be able to use hdparm instead, like this:
sudo hdparm -S 0 /dev/sdb]]>