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I see you need help in upgrading the SSD, on HP Pavilion Gaming Notebook - 15-ak002nl. Don't worry as I have a few suggestions which should help you.
After reading your post, I did go through the Product specifications of your product and found that you have 1 TB 5400 rpm SATA hard drive installed on the PC.
Next thing, I would suggest here is to go through the Maintenance and Service guide of your HP notebook, and found that your PC supports M.2 slot for the solid-state drive.
Also, you can try this suggestion:
Shut down the computer, remove the back, and remove the HDD. Then, try starting up the laptop, and that should boot from the SSD.
Then, shut down again and reinstall the HDD and check.
Hope this helps! Keep me posted for further assistance.
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