I sent my 6Plus to do battery replacement. They said that my battery is fine even though I have around 1400 charge cycle. And if the batter doesn't last whole day, it is likely to be bloated. So, they went ahead and take a look and then came back to confirm that it is bloated. Bloated battery they cannot replace the battery and so, they want to send to Apple for a 1-1 phone replacement for RM$239 (forgot exact amount). They passed the phone back for me to think if I want to do a 1-1 exchange. My phone was fine.. and I worry if I exchanged to a refurb one there will be NEW problems in the future. Sometimes, I feel these guys are just lazy! They rather not spend 3 hours to fix and suggest a replacement !

Just came back from Machines, so my battery was bloated. Only option they give is pay RM199 for a new iPhone 6S.
Not bad I guess...

My phone is a bit bent, but I don't think that was from the battery lol
Easiest way would to check if it is new would be the model number and the warranty.
https://appletoolbox.com/2017/11/how-to-tel...or-refurbished/

Well assuming it is a new phone la lol. But from what i've read, Apple's refurbished sets are usually better than newer units since they go through more stringent tests and most of the internals are new.
lol sadly my old model is only a rose gold 16gb.
But weirdly the invoice he typed in the model as grey 64gb 
Hopefully they replace the phone according to his error