It seems to me there are two problems here:
- 8 kg of tieguanyin covers only quite a thin layer in an oven that size. That means the tea is either over baked or baked with a too short duration.
- Recent autumn harvests of tieguanyin are typically very short fermentation and short of initial drying to maintain their floral aroma. These teas are NOT suitable for both storage for maturing and for rebaking: they are too much like green tea. To turn around that the process is too complex for me to explain here.
The mentioned article has briefly discussed that too. I am sorry abt your situation. However, it is possible that if the tea is not over-baked, you can try resting it for 6 more months and give it another round of slow fire. It will not be a magnificent tea, but the grassy smell maybe killed and the taste a lot more acceptable.
