Except he doesn't know what a microwave is, let alone what it means to 'ding' it. Renji in this case is the English word range, and is thus written correctly in katakana, not hiragana as shown. This is largely equivalent to a mispronunciation or misspelling.
The items will be happy if the one who uses them knows the correct way, right?If it interests you, you can have it.
Go ahead, take it.Eee! Really? But...wouldn't that be bad?Moreover, I couldn't see how to use it.
Ding it in a miclowabe oven or something...?
ちん or チン(する) means to make something hot using a microwave oven. This comes from the early microwaves (which used an analog dial timer, rather than a digital one) ringing a bell when the timer runs down.