Bno055 i2c address is 0x40 but why

I want to drive two BNo055 orientation sensor with my arduino but when I attempted to change the I2C address on one of the sensors so that it becomes 0x29, it instead changed to 0x40. Form looking online it appears that this is HID-I2C. How do I switch it back to normal?

What are you doing? The data sheet says the address is 0x28 or 0x29 depending on ADR. If you applied 5V to ADR then you may have killed the chip.

Just trying to use both sensors on one Arduino. I could just use two Arduino’s and have one Arduino feeding data into the other but this is cheating.

I may have killed it with the 5v as you mentioned but I don’t remember doing this. I read on other forumz that 0x40 is an address for HID-I2C which is something to do with pins PS0 and PS1. I am thinking that if I haven’t destroyed the chip already maybe there is a way to revert it back to the normal id’s.

You are right, see the Bosch datasheet Table 5-1: Pin Description.
I2C is selected by both pins connected to GNDIO. GNDIO should be connected to GND on the board.

Sorry, I also didn’t mention that both my PS0 and PS1 pins are empty so presumable 0 already.

Why don't you simply check it?

Yes I grounded both and still get 0x40 using the I2C scanner code