Sorry, but the SME HTA key is still a T6 torx.
refer to page 14 (Step 421):
https://sme.co.uk/audio/wp-content/uploads/sites/1/2016/12/SME-series-iv-instructions.pdf
refer to page 14 (Step 421):
https://sme.co.uk/audio/wp-content/uploads/sites/1/2016/12/SME-series-iv-instructions.pdf