[Dell Inspiron 1525, SigmaTel STAC9228] No sound at all. Internal Speaker Not Detected. Dummy Output. After Upgrading From 19.10 to 20.04 LTS Focal

Internal speakers were working fine until I upgraded the system from 19.10 LTS to 20.04 LTS on April 23, 2020.

Uninstalled and reinstalled alsamixer and pavucontrol, but of no use.

Killed pavucontrol and reloaded alsamixer numerous times, but of no use. (`pulseaudio -k && sudo alsa force-reload`)

Waited for two kernel updates, but of no use. Presently on 5.4.0-29.

Tried upgrading the kernel even up to 5.6, but of no use.

The Intel sound card is not getting detected.

Tried every trick like adding "options snd-hda-intel dmic_detect=0" in the /etc/modprobe.d/alsa-base.conf, but of no use.

Out of the two external audio output sockets for headphone, one is working. So I can either connect a headphone or an external speaker to this jack to tide over the crisis for the time being.

ProblemType: Bug
DistroRelease: Ubuntu 20.04
Package: alsa-base 1.0.25+dfsg-0ubuntu5
ProcVersionSignature: Ubuntu 5.4.0-29.33-generic 5.4.30
Uname: Linux 5.4.0-29-generic x86_64
NonfreeKernelModules: wl
ApportVersion: 2.20.11-0ubuntu27
Architecture: amd64
AudioDevicesInUse:
 USER PID ACCESS COMMAND
 /dev/snd/controlC0: raj 10952 F.... pulseaudio
CasperMD5CheckResult: skip
CurrentDesktop: ubuntu:GNOME
Date: Fri May 1 09:54:23 2020
InstallationDate: Installed on 2016-12-20 (1227 days ago)
InstallationMedia: Ubuntu 16.04.1 LTS "Xenial Xerus" - Release amd64 (20160719)
PackageArchitecture: all
SourcePackage: alsa-driver
Symptom: audio
Symptom_AlsaPlaybackTest: ALSA playback test through plughw:Intel failed
Symptom_Card: Built-in Audio - HDA Intel
Symptom_DevicesInUse:
 USER PID ACCESS COMMAND
 /dev/snd/controlC0: raj 10952 F.... pulseaudio
Symptom_Jack: Speaker, Internal
Symptom_Type: No sound at all
Title: [Inspiron 1525, SigmaTel STAC9228, Speaker, Internal] No sound at all
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 06/27/2008
dmi.bios.vendor: Dell Inc.
dmi.bios.version: A13
dmi.board.vendor: Dell Inc.
dmi.chassis.type: 8
dmi.chassis.vendor: Dell Inc.
dmi.modalias: dmi:bvnDellInc.:bvrA13:bd06/27/2008:svnDellInc.:pnInspiron1525:pvr:rvnDellInc.:rn:rvr:cvnDellInc.:ct8:cvr:
dmi.product.family: Inspiron
dmi.product.name: Inspiron 1525
dmi.sys.vendor: Dell Inc.
mtime.conffile..etc.modprobe.d.alsa-base.conf: 2020-04-26T17:25:43.583147