Bios update did the new update on my hp nx7300 after the update the system will not boot. all I get is the power light and the sound mute light

all that work on old Compaq why?
if the DC pack voltage is in spec then its ok.
a voltmeter tells you that easy, we, when lids off and at the internal jacks pins, under full load.
most laptops, had many processor choices, and up to 3 power packs matching that and up to 3 video cars, my HP5840w has that.

if BIOS screens are dead, you lost power, Im sure screen is ok)
BIOS most always work its resident in ROM and always works.
even with HDD /SSD removed.
its the acid test for all PCs.
this,Since the days of IBM PC Jr.... (with rom packs)
yes, older than dirt.

The main problem I assume from what you are reporting is the computer is powered up. but will not boot? Forget the Battery, lets look at the boot process. Considering that the computer has power, the CPU is sending instructions to the hard drive, Please Boot and Start Up. If the Hard drive is defective, it will not obey any instructions to start because the Boot Feature is not operative. Most likely the problem. Remove the hard drive and replace it with a new drive. The new drive is partitioned and ready for the operating system to be applied. You will need a new updated OS (Operating System Win 10) to boot and add programs. Replacing a hard drive is easy. Open the case, locate the hard drive, disconnect it, remove, and look at the details printed on the drive. Usually a SATA drive. You can purchase a new drive on Amazon for $30. This is dependent on the capacity, the 1Gig are about $40. In reverse, put the new drive in the old drives slot, hook up the wires like they were with the previous drive, and with the new Operating System disc inserted into the CD/DVD drive, turn on the computer. The CD/DVD should spin and on the monitor, show the start up for the Installation of the software. It asks for the licensed Key from the OS container. Just go from there. When complete, the new hard drive will be formatted and contain the WIN OS. Now you can boot the computer and add new programs. As for the old drive, if it was dead, you may have lost all data. Always do a back up along the way to preserve valuable data. Using USB Sticks is a good method.

remove battery boot with a/c only bad battery will hang up system

Go to BIOS to check the reliability of hdd or if you have a software tool such as "Avanquest System Suite" use it to boot machine from scratch. It will tell u what is really wrong.

u need to disable onboard sound hardware in BIOS

Here is the link for BIOS update
http://h20000.www2.hp.com/bizsupport/TechSupport/SoftwareIndex.jsp?lang=en&cc=us&prodNameId=3310302&prodTypeId=321957&prodSeriesId=3310301&swLang=8&taskId=135&swEnvOID=2094

Select the operating system for which you want to upgrade your BIOS and download the BIOS and upgrade it.

Below is the link on how to upgrade BIOS fot HP PC.

http://h10025.www1.hp.com/ewfrf/wc/document?lc=en&cc=us&dlc=en&docname=c00007682

Note : Your PC might be Unusable if BIOS Upgrade is fail. Please do it with extra care.

check in control panel yourt sound devce is not mute.
Also check speaker works correctly.

Then uninstall audio driver then reinstall again.
You can get driver from here

http://h20000.www2.hp.com/bizsupport/TechSupport/DriverDownload.jsp?prodNameId=3310302&lang=en&cc=us&taskId=135&prodSeriesId=3310301&prodTypeId=321957
then check.

Forgot HP laptop password? Click this link.

I guess your battery needs to be flash.

HP has identified a hardware issue with certain HP Pavilion dv2000/dv6000/dv9000 and Compaq Presario V3000/V6000 series notebook PCs, and has also released a new BIOS for these notebook PCs, version F.39 for dv2000/V3000, and version F.3D for dv6000/dv9000/V6000.

Click HERE to update your BIOS