Hi,
Why not try ifixit?
They have a compatible [https://www.ifixit.com/Store/Parts/HP-Beats-Special-Edition-15-p390nr|battery]. According to the link it has a lifetime warranty, barring normal wear and tear etc. Take note of the shipping restrictions, however.
Alternatively, search online for ''756743-001'' to get results for suppliers that suit. Check their reviews, returns policy etc to help you decide which one to go with.
The part number listed above should be printed on your battery if you wish to verify that it is the correct one. If not search for the part number listed on your battery.