Start buttons don't work after battery change Adidas Sports Timer

You will have to open your watch, because the contacts or contact springs are not stiff enough, so, you need to make them stiffer.
Do as follows:
1) Open your watch caseback
2) Extract the movement (carefully and using tweezers), do not touch dial with fingers,
3)Take small brush and lighter fluid (ZIPPO) and clean all pushbuttons in case from inside and out pushing them rapidly, then use dust blower to dry the fluid out,
4)On the movement you will see contacts corresponding to each pushbutton on the case. Use needle or sharp metal pin to clean (scrape) off any visible residue from these contacts till they are shiny.
5)Pull all contacts on movement sligtly outwards using tweezers but be careful not to brake. This will make them stiffer.
6)Reassemble the watch and the problem should be sorted.
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