After some troubleshooting I fixed this! I’m going to post a detailed write up here for anyone who might come across this in the future:
Issue
Sys-whonix is unable to connect to the tor network due to IPV6 being disabled. This does not affect the connectivity of sys-net and sys-firewall.
Diagnosis
To figure out if this is the same issue you have, you can use the command that @MellowPoison posted above: sudo systemctl status qubes-network-uplink qubes-network-uplink@eth0 qubes-network-uplink@eth1 | cat
In the output for this command, look for errors regarding ipv6. This is the line I saw that gave it away:
Sep 08 23:16:34 host setup-ip[1277]: Error: ipv6: IPv6 is disabled on this device.
Solution
To fix this, open a dom0 terminal and type the following commands:
qvm-features sys-net ipv6 ''
qvm-features sys-firewall ipv6 ''
qvm-features sys-whonix ipv6 ''
I found this solution in this forum post: Sys-whonix cannot establish any tor circuit - #17 by rrn
In his post he did not mention doing the command for sys-whonix, but I found that doing only sys-net and sys-firewall did not work for me.
Notes
I actually do not think this was related to the power being cut to my machine. I have a vague memory of messing around with something to do with ipv6 in the same session before my power cord got yanked, so it was likely that that caused it rather than the power being cut.
Thanks for everyone’s help! <3