What is the best way to promote your newly launched brand in the market a) through the existing sales team, b) through marketing activities.?

Depends on the product and the market.

For product you named, which is technical related commodity if I am not mistaken, I would say sales team and some marketing activity to back up the sales team (trade and direct marketing)

We should use the both teams , Marketing is responsible for suppliers  and also for give u the chance of sharing the market your new brand by many ways and the most effective way now a day is the  internet , Sales is the main way to show you what is the real state  of  your brand and to make the plan is full up from all the sides .

Obviously with marketing activities and current sales team.

I have only one thing to say about this question:

Marketing without data is like driving with your eyes closed!

Seriously, how can we answer without proper information?

For so long the debate of the difference between marketing and sales has been discussed among experts, and their findings stated that sales and marketing should go hand-in-hand.

Depending on the marketing plan, there will be a direct effect on the performance of sales. Also, sales has a direct impact on the marketing strategy itself because it is the responsibility of the sales department to communicate the feedback of the market to the marketing department in order for them to alter their plan according to the market requirements.

So, the answer to the question is a combination of both.

Good question. As known the marketing activities starts before the product manufacturing and service given. Then to promote our newly launching brand has to be started through good marketing activities as per the clear plan to build up a brand for this product or service. The marketing includes  the equipment and products as well as their spare-parts and loose material with their services.

Approach the OEMs directly through marketiing activities like making presentations to them highlighting the unique selling points

I say both Sales Team + Marketing Activities.

Also by free sampling..Discounts..Promotions..schemes