Compaq Presario 700UK Cmos Battery Replacement

I was also unable to find a service manual for the 721UK online.  However, the Presario 700 series apparently used common parts across many models:

700, 700AP, 700CA, 700LA, 700UK, 700US, 700Z, 701AP, 701CL, 701EA, 701FR, 701US, 702US, 705, 705CA, 705EA, 705US, 709EA, 710, 710CA, 710TC, 710US, 711, 711AP, 711AU, 711CL, 711EA, 711TC, 712EA, 712LA, 713EA, 714EA, 715, 715CA, 715US, 716EA, 717, 717RSH, 720, 720AU, 720CA, 720JP, 720US, 721, 721AP, 721CL, 721EA, 722, 723EA, 723RSH, 724EA, 724EAD, 725, 725AP, 725AU, 725CA, 725EA, 725LA, 725US, 730AP, 730AU, 730CA, 730LA, 730US, 731AP, 731EA, 731US, 732US, 734RSH, 735CA, 735LA, 737EA, 700A, 700D, 700EA, 700LB, 700ND, 700TC, 701JP, 701LA, 701Z, 701ZW, 702AP, 702EA, 702N, 702NA, 703AP, 704JP, 705JP, 706EA, 710EA, 710JP, 710Z, 711LA, 712, 712AP, 712AU, 712ZA, 715AP, 715EA, 715JP, 717EA, 718EA, 719EA, 720AP, 720EA, 720LA, 720TC, 721AU, 721LA, 721PT, 721UK, 721US, 722AR, 722EA, 722US, 723IL, 723RS, 724AP, 724AU, 725AR, 725JP, 726EA, 727EA, 728EA, 729EA, 730JP, 730TC, 731CL, 731LA, 731PT, 732AP, 732EA, 732IL, 733EA, 733FR, 734AP, 734EA, 735AP, 735AU, 735EA, 735US, 736EA, 738EA, 739EA, 7XXA, 702JP, 703JP, 717RS, 734RS

This being the case, if you can find a service manual for any of these models, it will probably be of assistance for the 721UK.

On the bottom of the laptop is a sticker with P/N (part number) and it always ends in #ABA.  What is that number (i.e. RG828UA#ABA)?

Hi
Theres no ABA number, only
Series 2130
and Model Number 700UK
Serial Number 1V1AKDKWD3FE
Badged under screen Presario 700
Rgds

Many thanks