WIFI gets HARD BLOCKED on Ubuntu 20.04.2, HP-15 series

hard blocked it is a physical problem... usually. Possibly you have switch button on the laptop case

Not an Ubuntu/software related solution..it is hardware related.. For the hp 15 series of laptops(old ones), if any one facing similar issue and tried all the above steps, then it is cz of the wifi card malfunction..it sends an off signal..to the input slot.. Os interprets it as a hardware switch.. In my case the card is already dead... both the wifi and Bluetooth, and I'm using an external adapter.. So I simply remove it (not simply, cz hp 15 series are quite hardly assembled, reaching inside takes some effort, but can.. if you got a nice set of screw drivers). get [your model no] manual pdf.. follow it to reach out to wifi card.. [If you didnt want to unplug the card, mask the pin 20 (as in picture - of total 52 pin connector, odd-even pins on both sides) use an insulation tape then cut it with blade to achieve good masking of the pin, refer the comment for details, and also visit this page to get more details on mini pci3 connector] and finally thanks @chili555 for the driving comment..

In Ubuntu 21.04, I executed

sudo rfkill unblock all

Then I updated the initramfs

sudo update-initramfs -u

...and this actually worked.

I don't know why it worked, but I wanted to share this as something you could try.

(Note: With Ubuntu 21.04, I've also had to add GRUB_CMDLINE_LINUX_DEFAULT="acpi=force" in /etc/default/grub for a shutdown issue unrelated to this problem. Remember to execute sudo update-grup if you make this same change.)

Background

I have a 2017 HP Spectre x360 Convertible 15-bl1XX, and this computer does not have a physical Wi-Fi switch nor a setting in the BIOS to enable/disable Wi-Fi. In Ubuntu 19.04, the ✈ F12 key worked flawlessly. (It did not work in 18.04).

In Ubuntu 21.04 I have an issue: If I enable Airplane mode using the ✈ F12, I am unable to turn on WiFi again by pressing this same key.

So I tried the "fix" in this answer.

All of a sudden, my Wi-Fi was hard-blocked:

1: phy0: Wireless LAN
    Soft blocked: no
    Hard blocked: Yes

The Wi-Fi on this laptop has never been hard-blocked since I have owned it, so this was quite surprising.

No matter what I tried, the (new) hard-block persisted.

Finally, on a hunch, I executed sudo update-initramfs -u, and this resolved the problem.